My question is this, I’ve been in a relationship for 4 years. I just recently found out that back when we first started talking and about to start dating, she had to take a trip to go get a divorce that was already in the works, finalized.
When she went to CA from FL to do that, she ended up fucking someone there she used to hang out with (before she left for CA we were having sex,) then she asks me to pick her up when she got back and at the time I didn’t know she did this till now (4 years later.) So now in my head I just realized that we had sex, she left, had sex with someone, then came back and had sex with me. Should I be allowed to be mad? In legalities, we weren’t officially dating from her words.
LemonVibe 
Ok so four years ago someone who wasn’t dating you yet, so therefore was free, had sex with someone even though she had sex with you?
No dude. You aren’t in the right here. She wasn’t dating you yet. You have a right to feel hurt, but honestly if I had to deal with this (and I’ve been married now 20 years) I’d leave you. You sound very controlling.
You weren’t dating so this wasn’t cheating. She was free to have sex with anyone she pleased as you two were not committed at the time. Also, this happened 4 YEARS ago!! I don’t see no point in dwelling on it.
Was it wrong of her to not tell you? Yes but she did not have to tell you. The talking phase is NOT commitment!