Melancholia...
I don't know what advice to give. I'm a real 'hate the sin, love the sinner' kinda person, but sometimes that doesn't come across very well... so if I start sounding judgemental I'm really sorry - it is not my intent.
Making a list of random thoughts...
1. The Church teaches that masturbation* is wrong. Always.
*Meaning one person, on their own. Mutual masturbation as part of
foreplay is completely different.
I'm sure you know how to read the Catechism

, but here it is again for the lurkers:
The various forms of chastity
2348 All the baptized are called to chastity. the Christian has "put on Christ,"134 The model for all chastity. All Christ's faithful are called to lead a chaste life in keeping with their particular states of life. At the moment of his Baptism, the Christian is pledged to lead his affective life in chastity.
2349 "People should cultivate [chastity] in the way that is suited to their state of life. Some profess virginity or consecrated celibacy which enables them to give themselves to God alone with an undivided heart in a remarkable manner. Others live in the way prescribed for all by the moral law, whether they are married or single."135 Married people are called to live conjugal chastity; others practice chastity in continence:
There are three forms of the virtue of chastity: the first is that of spouses, the second that of widows, and the third that of virgins. We do not praise any one of them to the exclusion of the others.... This is what makes for the richness of the discipline of the Church.136
Offenses against chastity
2351 Lust is disordered desire for or inordinate enjoyment of sexual pleasure. Sexual pleasure is morally disordered when sought for itself, isolated from its procreative and unitive purposes.
2352 By masturbation is to be understood the deliberate stimulation of the genital organs in order to derive sexual pleasure. "Both the Magisterium of the Church, in the course of a constant tradition, and the moral sense of the faithful have been in no doubt and have firmly maintained that masturbation is an intrinsically and gravely disordered action."137 "The deliberate use of the sexual faculty, for whatever reason, outside of marriage is essentially contrary to its purpose." For here sexual pleasure is sought outside of "the sexual relationship which is demanded by the moral order and in which the total meaning of mutual self-giving and human procreation in the context of true love is achieved."138
To form an equitable judgment about the subjects' moral responsibility and to guide pastoral action, one must take into account the affective immaturity, force of acquired habit, conditions of anxiety, or other psychological or social factors that lessen or even extenuate moral culpability.
134 ⇒ Gal 3:27.
135 CDF, Persona humana 11.
136 St. Ambrose, De viduis 4, 23: PL 16, 255A.
137 CDF, Persona humana 9.
138 CDF, Persona humana 9.
http://www.vatican.va/archive/ENG0015/__P85.HTM
Ultimately, this behaviour needs to stop, or he could be in trouble, eternally-speaking. But unless he sees it as a problem, this will obviously be difficult. As trite as it sounds, I recommend you pray that he have a change of heart.
As for him 'flattering' you by objectifying your body, instead of the bodies of women in pornos... it doesn't matter WHO is being objectified - it's not on. And one could argue it's even worse if he's using you, rather than some random pornstar. Why? Well your husband promised to love, honour and cherish you (or the other promise I forget) forever - and I'm not seeing any honour in him [wash my mouth][wash my mouth][wash my mouth][wash my mouth][wash my mouth][wash my mouth][wash my mouth] while you are asleep next to him. There's not much honouring going on with porn either, of course. It's still a very ungodly situation. I just see slightly different degrees there.
Looking at the Catechism again:
V. The Goods and Requirements of Conjugal Love
1643 "Conjugal love involves a totality, in which all the elements of the person enter - appeal of the body and instinct, power of feeling and affectivity, aspiration of the spirit and of will. It aims at a deeply personal unity, a unity that, beyond union in one flesh, leads to forming one heart and soul; it demands indissolubility and faithfulness in definitive mutual giving; and it is open to fertility. In a word it is a question of the normal characteristics of all natural conjugal love, but with a new significance which not only purifies and strengthens them, but raises them to the extent of making them the expression of specifically Christian values."150
The unity and indissolubility of marriage
1644 The love of the spouses requires, of its very nature, the unity and indissolubility of the spouses' community of persons, which embraces their entire life: "so they are no longer two, but one flesh."151 They "are called to grow continually in their communion through day-to-day fidelity to their marriage promise of total mutual self-giving."152 This human communion is confirmed, purified, and completed by communion in Jesus Christ, given through the sacrament of Matrimony. It is deepened by lives of the common faith and by the Eucharist received together.
1645 "The unity of marriage, distinctly recognized by our Lord, is made clear in the equal personal dignity which must be accorded to man and wife in mutual and unreserved affection."153
150 FC 13.
151 ⇒ Mt 19:6; cf. ⇒ Gen 2:24.
152 FC 19.
153 GS 49 # 2.
http://www.vatican.va/archive/ENG0015/__P55.HTM
Marriage is a tough gig. No question. Without mutuality it's even tougher.
It is your call what you do, but if I knew I was being regularly objectified by my husband, I'd sleep in the spare room to avoid it happening. Or better yet, I'd make him sleep in the spare room.
If you really want to change this situation, go find a good marriage counselor. (You might need to find a Catholic one who understands the moral issues with masturbation...) and talk about it with your husband. Hopefully he'll come around. And for yourself I'd get a spiritual director (a good, compassionate priest who is old enough to have heard enough confessions to know what REALLY goes on in marriages!) and talk to him about your side of the situation.
One more CCC quote and then I'm done
II. The Battle for Purity
2520 Baptism confers on its recipient the grace of purification from all sins. But the baptized must continue to struggle against concupiscence of the flesh and disordered desires. With God's grace he will prevail
- by the virtue and gift of chastity, for chastity lets us love with upright and undivided heart;
- by purity of intention which consists in seeking the true end of man: with simplicity of vision, the baptized person seeks to find and to fulfill God's will in everything;312
- by purity of vision, external and internal; by discipline of feelings and imagination; by refusing all complicity in impure thoughts that incline us to turn aside from the path of God's commandments: "Appearance arouses yearning in fools";313
- by prayer:
I thought that continence arose from one's own powers, which I did not recognize in myself. I was foolish enough not to know . . . that no one can be continent unless you grant it. For you would surely have granted it if my inner groaning had reached your ears and I with firm faith had cast my cares on you.314
2521 Purity requires modesty, an integral part of temperance. Modesty protects the intimate center of the person. It means refusing to unveil what should remain hidden. It is ordered to chastity to whose sensitivity it bears witness. It guides how one looks at others and behaves toward them in conformity with the dignity of persons and their solidarity.
2522 Modesty protects the mystery of persons and their love. It encourages patience and moderation in loving relationships; it requires that the conditions for the definitive giving and commitment of man and woman to one another be fulfilled. Modesty is decency. It inspires one's choice of clothing. It keeps silence or reserve where there is evident risk of unhealthy curiosity. It is discreet.
312 Cf. ⇒ Rom 12:2; ⇒ Col 1:10.
313 ⇒ Wis 15:5.
314 St. Augustine, Conf. 6, 11, 20: PL 32, 729-730.
http://www.vatican.va/archive/ENG0015/__P8R.HTM
I think this is a good one. It's from the Ninth Commandment section. We all need to strive to be pure of heart. And it's hard. But we can do it.
I hope this was in some way helpful
HofB