Insanely jealous.

Hello!

First of all, a bit of context: a suffer from borderline personality disorder (BPD). I don't want to blame everything on BPD - as I believe I have to take responsability for my actions - however I think it's a disorder that affects very strongly the way I think and feel about things, in a way that sometimes may be very distant from reality. So it's up to you to tell me whether you think I'm going nuts again or not:

Here goes: last September, my significant other got in touch with his highschool sweetheart (through
facebook). It had been about 20 years since they last saw each other and I wasn't very happy to see they were friends on facebook. She's very pretty, lol. Anyway, he was already friends with her sisters and mother before she joined facebook, and they also have a lot of friends in common.

So far everything seems normal - ok, I felt a bit uneasy and started following her posts every single day, paranoia thing, but at the same time felt that it would be normal for them to catch up.

A month later I realised she'd gone through his whole page on facebook and "liked" something he had posted a year before, when they weren't even friends. And the post she "liked" was a quote on "how to love a woman". Out of all the things he posted, that's what she liked.

Ok. Once again, she could have been checking his whole page out of curiosity. And could have liked that quote. Simple. But very uneasy for me.

By now I've had countless nights of nightmares with her. He doesn't know about this and when I asked about her, "oh it's nothing, but we were really close friends and have normal conversations!"

So I thought: it's ok to catch up and maybe they're not even talking anymore.

Two months ago, I checked his computer history and saw that "in the last 7 days" he'd been checking her photos - about 20 and had exchanged messages with her, but wasn't able to read them. In the last seven days. So I asked him: have you talked to her recently? He said no. I said "it's in your computer history". He said he didn't remember. That it was probably something unimportant". He acted very deffensive. I said "let me see then. Let me read it". He wouldn't let me. He didn't let me.

Now you may say that I had to right to a) not trust him b)go through his things c)ask him for his personal stuff and that he was right to say no. But I don't find this natural. At all...if I had nothing to hide I'd show it straight away.

He then said he had already deleted the conversation and that he didn't remember it. That sometimes they wouldtalk about trivial stuff, that she was having a hard time because her husband had left her with two kids. And I'm like wtf, one thing is catching up, the other is having kind of intimate conversations that I don't know about.

She lives in a different state so I'm sure he hasn't seen her, but in two months he'll have to go to her state for a few days (work) and I'm terrified they'll meet up. He would never tell me even if it was innocent. And I also don't think it's very appropriate for them to meet, although some of my friends say it may be natural. Well, it COULD be natural if she was a long time lost friend, but she's his ex-girlfriend. And very hot too.

I know, there has to be trust in a relationship but I'm finding it very hard to deal with this. I've tried talking to him but he dismisses everything. He once told me that if I wanted he would delete her but I said no. Don't wanna go that way.

Jeez, I'm damned. Your thoughts on this?

P.S. Also: pretty much every woman that he comes close to I think he'll cheat on me with her. Or I think he'll want to have something to do with her, and that she's probably easy going and happy and that he'll prefer her to me. It's just so hard living like this. But I don't know if it's just me, or if he's really doing something that triggers this. He's divorced and I know he has cheated in the past (not with me).
I don't know if I'm being sick or if it's my intuition telling me to pay attention.