Hi Layla17, just reading through your thread, what a horrible time you are having..
I completely understand about that sick feeling in the pit of your stomache, you just cannot escape this situation can you?
My friend is a born again christian and didn't have sex until she got married-she was with him for a couple of years even though she has a 7yo by another guy?
Anyway, I think your partner is having a bit of a breakdown, have you suggested visiting the dr for anti depressants?
This woman is a shoulder to cry on and because you have been part of the problem(re the stress of life/family probs) he has turned to her.
I believe YOU can get him back and WIN as I sort of see it as I feel as though this woman is a wee bit competative?
IMO, if you can muster up some inner strengh and say to yourself NO! i'm not having this anymore, and go on your holiday, you will be showing him that you are getting on with your life and showing him strength of character. That may look more attractive to him than you being weak, unthough completely understandable in your situation.
Try not to think about what he may get up to while you are away, this will drive you mad, just think that i'm gonna try and pull it together for my kids and if he's gonna do it, hes gonna do it, there is nothing you can do.Easier said than done I know but you know what I mean?
In the mean time, do the Relate thing as it obviously keeps the lines of communication open.
Good Luck ok