My husband just found out he has 3 year old twins. Is he still in love with her?

Never jump into a relationship where that person has just broken up with another. That was the mistake you made. What happened was he never fell out of love with her and he figured he would find someone else. Now that she came back he wants her back and the fact that she had his kids will make the situation worse because he's going to want to be in their lives and I'm sure the woman will be in his life a lot too. Honestly all you can do is stay married and see what your husband does in the situation and if it doesn't work out there are always other men. Just don't be disrespected by her or your husband. I hope it all works for the best.