Don't let your alien get to you. He is not together enough to admit that he is the one that is turning everyone else's lives upsidedown - so he is looking for someone to blame - and who better than you! He cannot handle taking responsibility for his own actions - so he looking for and/or manufacturing reasons for blaming you and to justify his own actions.
As for the love thing - the man you M is the one you love. The alien that he is today isn't too loveable... I suppose we DB to see if the alien leaves and returns the P we M to us. The man he is right now is overwhelmed by his own gunk and incapable of thinking of anyone or anything else beyond himself. Kinda like a drowning man - you have to detach from him otherwise he will pull you down with him.
Your boys probably will cling to their dad for awhile - this must be such a destabilizing and scary time for them too...to see their father moving out. I think they know that you will be there for them - so they can afford to take you for granted - that is actually a testament to their faith in you. You are their rock. Your H's actions are probably causing some serious nervousness for them.
I am glad that your mother is agreeing to give you your space.
I can relate to how you are feeling - numb - stunned that this is actually happening... I know - take care of yourself. Take one moment, one day at a time. And pamper yourself a little extra...
I know this post is all over the place - I hope I have helped...