I'm not sure if you are still watching this thread OP, but wanted to write to you anyway. You have had MANY posts of leave the bastard, and I wanted to make one from the other foot (so to speak).
I went through a similar thing (although different in that it was a drunken one night stand with a stranger, so no emotional connection) and reading your posts brings me back to how I felt at that time.
I will say now, I decided to stay with my partner (shock horror!!!) and are still together now.
My first bit of advice would be not to rush into making any decision that is driven by emotion. You (like me) are financially constricted, and have a young DD to consider. Living under the same roof is not horrific, if your on polite enough terms and have set clear boundaries then don't feel like your not 'acting' the way you should by shipping him out the door. Sometimes life isn't that straight forward and isn't possible. But you have time, nothing needs to be decided in the next week, month or even few months.
My second bit of advice, would be to quietly sit back and observe his behaviour. Watch what he does without being prompted or asked, allow him the space to make it up to you, to begin to put things right. You did not create this problem, so it is not up to you to fix.
Thirdly, and I say this with nothing but kindness, don't allow ego to cloud judgement. And by that I mean, don't push yourself into making a decision or choice because it socially is the expectation to instantly bin some one who has been unfaithful. No-one on this planet has to live the life you do, nobody see's the intricate details of your relationship apart from you. I really struggled with this aspect, the self judgement of feeling weak and a pushover for even thinking about remaining in the relationship.
There is nothing weak about remaining in a relationship where it is wonderful 99% of the time. Yes, the pain and devastation that the 1% creates is nothing to minimise. But the 1% doesn't have to define your marriage.
Only you knows what is right for you, your family and your life. And whatever decision you make, has to be the one that feels right for you.
If it helps, me and my partner are very happy together now. Its been 4 years, its taken ALOT of work both individually and together. And I can honestly say it was one of the most difficult emotional journeys I have ever been through, but for me? It was worth it. I am glad I gave him a second chance. I have now managed to forgive, never forget, but forgive.
Whatever you chose, there is light at the end of the tunnel.
Please feel free to private message me if you need, sometimes a stranger over the internet can be the perfect sounding board.
Wishing you all the love and support possible x