I have a boyfriend and not too long ago I realised he was becomming my FP, I spoke to him about this and with what he understands about what an FP is he wasn't too fond of it but was also understanding of it. I hadn't struggled too much with jealousy, I got the occasional "why won't he message me back" and "I wish he were spending time with me right now instead of his friends" but I never let it create an argument, I forced myself to understand that he's probably just busy and that he has the right to spend time with others. 

Recently I've been getting more and more jealousy when it comes to girls in his life or even girls who were in his life (it's probably got to do with the fact that my life is falling apart elsewhere). I get pangs of jealousy and an ache in my chest when I see girls in his friends list or messages, there's nothing ever innapropriate in there so there's really nothing I should be worried about, we've had our complications in that area but whatever mistakes were made are dealt with and most of the time it's just miscommunication or misunderstanding. 

An issue has come up and it's caused me to spiral out of control, I'm obsessing about what his thoughts are and if he's thinking of someone else, I'm uncomfortable with these pretty girls in his contacts and worst of all, he had a crush on a girl 2 years ago (before we were dating) and I'm getting jealousy over that. 

I don't know what to do about it because it was a long time ago, before me and it was just a crush, nothing ever even came of it but in my mind I think "but he's supposed to be mine". My mind tortures itself with intrusive thoughts and images of what he was doing and thinking and saying those two years ago to her, I'm plagued with images of him lusting over her despite him reassuring me it's nothing like that and that I'm the one he's with now. 

To make the jealousy and insecurity worse, the first time we dated in early highschool he dumped me because another girl asked him out and he liked the affection, this was like 5 years ago and completely irrelevant to our relationship now but I sit there worrying that if a pretty girl came and gave him attention he'd leave me again. 

None of it makes sense and it's all so irrational but it's plaguing my mind with intrusive thoughts that I can't shake and it's having an impact on our relationship, it's not his fault and it's not fair on him when I'm upset and complaining over something so small that happened years ago. I also don't want to be that girl that tells him he cant be friends with other girls but I also can't control the pain it puts in my chest.

I don't know what to do, I can't let go of the past

TL:DR My boyfriend has become my FP, never had too much of a problem with jealousy before but now it's getting worse. I get aches in my chest when I see girls in his messages or friends list and I can't let go of the past, I'm getting jealous over things that happened years ago even if they're as small as a crush and it's having an impact on our relationship