So in a nutshell, you're saying there's no situation where someone can be allowed to remarry a 2nd spouse? That the person who cheated on you, left you, married a new person, and you, the one cheated on, has to remain as you are...never...ever...marrying again?
Biblically, yes.
Because God never recognized the divorce. To God it is a covenant, and only death nullifies it.
As Jesus put it
Wherefore they are no more twain, but one flesh. What therefore God hath joined together, let not man put asunder.
See, they're no longer two individuals, they are one, there's a bond. You can't just split a person in half and make 2 people. Same thing here.
Even Fornication carries that risk too. The mosaic law punishment for fornication? The 2 fornicators had to get married (or the man had to provide a virgin's brideprice to the father, if the father rejected that marriage). Why? because they were joined already.
The Apostle Paul warns us about this in 1 Corinthians 6
16 What? know ye not that he which is joined to an harlot is one body? for two, saith he, shall be one flesh.
So.. the person you lost your virginity to.. in God's eyes.. you've become one flesh with them, and that doesn't go away just because it was a one night stand and neither person ever saw each other ever again.
Paul goes into it further
17 But he that is joined unto the Lord is one spirit.
18 Flee fornication. Every sin that a man doeth is without the body; but he that committeth fornication sinneth against his own body.
19 What? know ye not that your body is the temple of the Holy Ghost which is in you, which ye have of God, and ye are not your own?
20 For ye are bought with a price: therefore glorify God in your body, and in your spirit, which are God's.
Because you've joined to God in one spirit, when you join to a harlot (not calling anyone in particular this name just going off the scripture here), you become one flesh, and that flesh, is the temple of the spirit. So what has been done is not only defiling your own body, but defiling God's spirit, by joining His spirit to a harlot, and Paul rounds it off with telling you it's not your own body and spirit to be off doing whatever you want with anyway.
anyway, sorry to get preachy about this..
But it sounds like this woman has reservations against you to start, and I'm just saying, it's probably not a good idea to pursue it because of the sin aspect which should make it easier for you to make a clean break out of it rather than agonizing over it.
and if she gives you trouble about it.
You can always lay on the biblical truth of her situation.