It should get better. The guilt should subside. However, kids are great at keeping the angst going and you and your son were already having issues before the pending divorce was announced. Sounds like gasoline was added to the fire. Family counseling could help all of these relationships if you can find a good counselor. He might need counseling on his own (good luck getting him to go, it would be nice if dad would encourage him to do this) so he can rant/vent to someone who is not you and has nothing vested in the relationship. As we all know, sometimes hearing things from other people can make what mom/dad say suddenly sound reasonable!
Lots of hugs for your daughter, it's so tough. If there's a counselor she likes at school that can help too if you don't want to find someone just for her.
Hugs to you. This is hard, hard, hard and anyone who thinks someone does this with a light heart is deluded.
I definitely understand where you are at. We told our kids two weeks ago. I always thought that it would be easier if the kids were older but that is not true. My two oldest kids are grown and, to be honest, have been the hardest. They have not known any other life but their parents married...happy or not. My 13 year old boy is handling things as well I would expect.
I feel the same about feeling guilty about tearing my family apart. My STBX and I have actually been very amicable. He is still living in the house but is looking for a place. I know I cannot live in this marriage...even after much doubting...I know it is the right decision. Many women on here have given me good feedback so you are in the right place for support.
Good luck! Kids are a challenge but no matter what they are the most precious gift. They will always treat mom the worst because we always love them and accept them no matter what.