You need to think of yourself at this time, is lamictal a mood stabilizer by any chance? I take abilify for that. and it really helps. But I think that yours sounds to be situational. I don't have any kids because my mother was abusive to hers. And I didn't want to repeat that pattern either. So I broke the chain at that point.
If you can make it by moving out, I think that would be a good idea. You can't help what your sister is going through and you have to take care of your needs. She will make it okay, I am sure. Or talk to her about
it and tell her that you can't be a live in baby sitter. Your patience is running thin. Maybe she will look after her grandson a little more instead of putting it on you. I truly understand where you are coming from. I think that this would be better than having it wear on your patience.
I hope that this has helped some, I am sure that there will be more people chiming in with some advice.
Luv and hugs,
fibromyalgia, Chronic fatigue, depression,allergies