For two years now (two years of dealing with a man who is addicted to EVERYTHING: crack, booze, gambling, food, money, women, porn, you name it) my mother (who NEVER tells me what to do in my life but who is a very strong and happy woman) has been telling me:
1. always follow your heart.
2. always follow your morals and your values.
And she is right. It got me through these past two years and I'm a better person for it.
You don't need to make these decisions right now and you shouldn't. In fact, all you need to do is follow rules 1 and 2 above. You are a good person and it is very rare that you find a person who will take care of someone else's children just because they care. Try not to worry about what will happen in the future. One day at a time baby!