What would you do in a complicated love triangle?

I find myself, as my question states in a complicated love triangle.
The first person I was with we ended up breaking up on rather bad terms. We were married and have been separated for almost two years also, in that whole time span I had not heard from her more then maybe three times and have one child together but now all of the sudden she wants to assimilate herself back into my life, She is a really nice person I feel like I still have lots of love for her and after being able to talk to her she seems to have matured a lot. I think of her as the one that got away, when we got together we were young and fresh out of high school.
Now the second person I just recently broke up with because while I have been away on work she has shown herself to be rather unfaithful and consistently immature, at least to my standards. With her we have twins I think of her as the person that could be great for me if she could just get her head screwed on straight.
As for me I am in a great financial situations and I chose to move and settle in to a new place in order to accept a promotion that will set me up in a comfortable life style. The problem is that now both ladies want to be a part of the new life that I’m going to start for myself. I’ve come to a fork in a road and both roads are filled with the unknown. How do I find out which one is best suited for me? How can let one or the other down? I love all my kids whole heartedly but somebody is going to get the dirty end of the stick. Lastly should I just let them both go and start my new life on my own? I’ve even gone as far as to chart the pros and cons for each of them….and it comes out rather uninviting.
And yes, they do both know about each other.