Its still a bit much that he got his mum to intervene on his behalf! I thought he was a grown up!
Letting go of the guilt is hard, I know. But you are allowed to have these feelings and you are allowed not to act on them as soon as you feel them! This was something that took a while for me to 'get'. I used to beat myself up for feeling guilty, sorry, angry and just about everything else! Now, over a year separated, I don't feel any guilt at all!! Sometimes, telling it as it is to misguided/well intentioned friends and relatives helps. Hang in there, it will get better.