Hi, everyone, I'm new to the board!
I'm so frustrating and confused and I've got nobody to talk to about my boyfriend...

I desperately need some1's opinion!
I and my BF been together for 2 years now, I've got 2 girls from my last relationship, thing's ok with my BF just we leave quite apart, he doesn't drive and if I didn't go up to his, he wouldn't come to mine, so we only get to meet up once a week while my kids go to their dad's!
Just about this time last year, my BF met this woman in the pub, and he invited her up to his flat while I was not there, and I walked in to them in the living room, nothing happened, they just chatting and drinking, my BF said they only just 'drinking mates', and I believe him, but she kept ringing and txted him all the time, most of these messages were deleted by my BF, when I asked him, we had a row and almost split up, but we thought let it go and things went quiet a bit, then after few months later, she started to txt him again, I went crazy and confronted her by ringing her, she admitted that she fancied my BF but nothing had happened at all, so that was the second time me and my BF almost split because of her! I hated it, since I regularly checking on his cell phone, I know it's wrong but I can't help it.
We have been quite happy since she'not ringing, till last Sunday, I found out he went out drinking and must've bumped into her in the pub, and he sent her couple txt messages first thing the next morning and said 'You shouldn't have kept me up all night!'....I felt sick in my stomach but I didn't say anything this time, I don't know what to think... I don't want confront him straight away just in case they just pure drinking all night...oh I really don't know what to do, my heart tell me to trust him but my head just all jumbled... god, should I be thinking the worst like this!
Please anyone, just say something ...PLEASE!!!