I think God sees the circumstances and motivations for your promise and recognizes that your promise was made foolishly. I'm sure He takes that into account in how He regards your promise. Scripture, though, has something to say about making promises to God:
Numbers 30:2
2 If a man makes a vow to the Lord, or swears an oath to bind himself by some agreement, he shall not break his word; he shall do according to all that proceeds out of his mouth.
I doubt God appreciates you making - or keeping - promises because of your cat's hacking. Recognize that what you did was foolish and disrespectful toward God and determine not to do it again.
As a person who once struggled a lot with anxiety and OCD, I can tell you that your OCD reveals that you have some fundamental misunderstandings about God and your relationship to Him. If you want to be free of your OCD, this must change.
Matthew 11:28-30
28 Come to Me, all you who labor and are heavy laden, and I will give you rest.
29 Take My yoke upon you and learn from Me, for I am gentle and lowly in heart, and you will find rest for your souls.
30 For My yoke is easy and My burden is light."
2 Timothy 1:7
7 For God has not given us a spirit of fear, but of power and of love and of a sound mind.
1 John 4:16-19
16 And we have known and believed the love that God has for us. God is love, and he who abides in love abides in God, and God in him.
17 Love has been perfected among us in this: that we may have boldness in the day of judgment; because as He is, so are we in this world.
18 There is no fear in love; but perfect love casts out fear, because fear involves torment. But he who fears has not been made perfect in love.
19 We love Him because He first loved us.