I would not be able to be a part of the family anymore. I know they would support me because they know what thier brother is like but it would be so hard for me not to be included anymore.
You are making an assumption that wouldn't happen. Your kids would still go to their cousins... so????
Work on you... go to an Al-anon meeting, focus on you and making you better. Read the power posts on the women in recovery forum... they've got some really good information. The more you know, the more you learn, the more power you have... but in reality... you do have the power to change you NOW..
Staying is hard. Leaving is hard. Either way it's a choice only you can make based on what's right for you...