Im already a very jealous person - concerned about his ex moving so close.

So I got very burned in my first marriage - my ex husband strung me along for months thinking oi was insane for thinking he was cheating. Turns out he was and had cheated with 2 the people I now know and suspected about. The whole time he maintained it was me with the issue for not believing him - I was right not too.

Its left me very untrusting. 

My new partner have been working on building my trust issues - initially not helped in the first 6 months by lost of contacts from a few of his exes. He explained they were just friend s and he has always remained friends I told him it didn't make me comfortable and that I wanted it to stop. And to my knowledge he did. Apart from one.

However one of these exes keeps messaging him via facebook and email and text. Initially I saw  the  a message came through so I checked his email and she had sent 4 and he hadn't replied. but she was implying he messaged her first. 

I checked his facebook messenger and there was a conversation which he had initiated within the first 6 months of our relationship and had stopped around the time I asked him to stop.  apart from a few from her with no reply - This was 2 years ago now a I confronted him about it and he promised that he hadn't replied and left them there so I could see as per my request. (as I said deleting things looked like hiding things) anyway 2 years later she had sent him 2 more emails and a few waves on facebook. he tells me when he receives them and that as far as far as i'm concerned : enough to believe him. 

NOW

I have just seen that she is advertising a roommate on facebook. now Im concerned she has moved in 30 seconds away from our house in a city thats huge and she has always lived the opposite end. I know she doesn't work around here and infant works for the local council so will have access to electoral roles and addresses etc.....

Is she hoping for some chance encounter or am I just reading into something that is pure chance because i'm such a paranoid bitch. Im 11 weeks pregnant and really stressing over him bumping into her at the local shop etc.....  They were good friends more friends than lovers and my biggest worry is that one night the baby will have us really tired he will be stressed and he will end up round hers. I know that she slept with him behind another one of his exes back so

a) she has no morals about sleeping with a taken man

b) he has done it before,  But this was a 6 years ago and we have been together for 4.

I am trying not to dwell on his past as I really believe he has change and he is besotted with me. but I don't trust her or her motives even though I don't even know her! 

someone just tell me I'm crazy and its hormones and trust issues!