(Name changed because of possible outing)
Sorry, this is a long post but am trying to give a full picture.
H and I have been married for over 20 years and have 3 DCs, 17, 15 and 10. I've suspected/known that H was having an affair with someone from his native country for about 18 months. In spite of confrontations, he'd always denied it until this year in April he admitted that he was having an affair and also said to me that 'as far as he's concerned, we haven't been married for 3 years'. (we were having sex until a year ago...admittedly, the last few months were totally awful but it was intercourse) He also had a breakdown at work, and since then has been signed on and off work with depression. He's started therapy and has been taking antidepressants. For me, our relationship is over - I've lost all trust in him, he's lied even when confronted with the truth, he's gambled away money, and over the years has treated me with no respect and even abuse. However, because of his depression, I constantly feel that I have to tread very carefully around him, which makes me resentful and guilty at the same time.
We're lucky to have an empty granny flat, and he sleeps there, but comes home every day, takes (more or less) part in family life, eats with us etc. So for the kids, 2 of whom are about to embark on significant years at school (A levels and GCSEs), there is a semblance of continuity. I have said to him that I'd like us to be able to continue in this house until after their exams (we wouldn't be able to afford the mortgage if not together); he has been saying that he wants to stay for another 8 (!) years to see our youngest through school. I'm filled with horror at this thought, but haven't said as much because of the depression etc. I'm not saying the kids don't know something's up, and the older 2 pretty much know that our marriage is over, but the youngest doesn't really, or at least no-one's had the conversation with him. I wanted to tell them everything a couple of months ago, but H resisted. He also said to me that he didn't really like his girlfriend, he was just with her because she listens to him et crap
Anyway, as he's been signed off again this month, he said he wanted to go to stay with his dad - his mother died very suddenly last year and that's caused a whole load of other issues. I didn't really believe he was just going to see his dad, but I thought he was being more honest with me and what can I do anyway? He was due back on Friday. On Thursday, I texted him to find out when he was coming back. No reply. On Friday he suddenly texted that he'd got his flight wrong and had missed it and so also his connecting flight. This is totally out of character. He went on about how bad he felt, how stressed it had made him. I replied that I didn't believe him and that I'd prefer a painful truth than a lie. Since then, I've had really weird communications, mainly from her, including her telling me that I should know how to behave better etc. I've deleted all her messages and am really trying hard to keep her out of my head. I know he's lied to her too and she thinks we're actually separated and have been for years; I don't think she knows that we still share a house and are, as far as outward appearances go, still married.
My question is: should I be fighting for normality to continue until the kids do their exams? I feel that for their sakes I should, but he is such a lying shit, I can hardly bear the thought of having him in the house. I'm also really nervous about what could happen - he promises one thing when he's here, but now it seems that was all just to make his life easier. He's supposed to be back this Friday and I need to decide how to deal with it.
Thanks for reading this far and for any support.