I've been with my partner for 12 years. We have a 4.5 year old son. We both work full time and DS is at nursery. I had a call from nursery today to say that DS was unwell and could I pick him up. I phoned DP, got his voicemail and left a message to say I was leaving work to collect DS (he normally does it). Picked a slighly poorly DS up from nursery, got the bus home and walking down the road, spotted DP's car in the drive. Very odd, as he hadn't told me he was working from home/unwell. He'd gone to work as normal in the am and we'd been emailing about various domestic things all day.
The front door was locked, with the key inside so couldn't open it. This was very weird as DP doesn't leave his key in the door. I knocked and then went in the side way. Came through the kitchen to find DP coming down the stairs saying X (friend from work) was there "helping him" as he had a back back 
I get the feeling that this was more for DS's benefit than mine as I immediately clocked what was going on from the look on DP's face. He told DS that she was in the bathroom but going in a minute and then said to me "we'll talk when she's gone". I took DS into the living room to read a book and she came down and left without me or DS seeing her. We set DS up watching TV and went to another room to talk.
DP immediately owned up to having "an affair" - his words. However, it had only been the second time. First time about a month ago apparently. He said he was sorry but didn't seem particularly apologetic. In face he almost seemed angry with me. He didn't seem surprised or upset weirdly. We had a chat which got quite heated (mainly on my part, DP just took what I dished out) and then I told DP to leave, which he did.
As background, our relationship has not been the same since DS was born. Our sex life in particular has taken a back seat to everything else and our communication got really bad a few months ago. We had a big row a couple of months ago, followed by a big, honest conversation about how things weren't going as well as we'd like and agreed that we'd like to make the effort to make things work. Since then I've been happier. Actually, really quite happy. We've been making plans for the future, holidays and days out etc, all happy family stuff. It was my birthday last week and DP bought me some lovely presents and took me out for a nice dinner where we had lots of fun and conversation about things other than DS. Admittedly, our sex life still isn't great but it's been better and something that I thought we were both working on.
But apparently it's not been enough for DP. He admits he's been stupid and selfish and went looking for what he was not getting at home. He's been exactly the kind of man I thought he wasn't. I had no clue this had been going on. I would not have thought he could ever do this. I feel utterly betrayed, humilated, violated (in my own fucking bed, for fuck's sake! Practically in front of our child!), disgusted and basically like a total fucking mug
What makes me feel most mug-like is that I miss him! I still want this relationship to work. I love him, even though I am utterly furious with him.
The plan is that he's staying with a friend. He's going to pick DS up from nursery as usual, bring him back here and then we'll talk more once DS is in bed. We've spoken on the phone tonight and he agrees he's been a utter shit. He doesn't want a relationship with OW (FFS, I never thought I'd use the term "OW" about my DP, or my relationship 
) but is not sure about a relationship with me. He loves me, loves DS beyond anything and loves our family and our home. But somehow he's scared of talking to me and telling me how he feels I laid my cards on the table and said that I was prepared to try and make things work but only if he really wanted to, was prepared to try as hard as I was, we'd get some couples counselling and he was to cut all contact with OW.
Am I being a total doormat? I am so furious with him and not ready to forgive yet but I do WANT to forgive. I don't want to break up my family over this. Can a relationship survive something like this?
I am doing OK, in general. My sister came over for moral support and to help with DS (who has been told that we've had a row and daddy has gone away for a few days, which has made me sad, hence the tears ) I am just wiped out emotionally now. DS is fine, recovered from whatever was wrong with him at nursery and has gone happily to bed without asking for daddy, which is a relief.
I just need some wise MNer advice. What the actual fuck do I do now?