I think it's best to go your separate ways. It's much better for a child to have two low-stress, loving homes than to have one that's full of contention. My parents divorced many years after they should have, and my sister and I still have some really horrible childhood memories from that time. After the divorce, we felt like we were finally able to relax and just be kids. As for my son -- he's even told me how much he loves the different houses now, and how much he loves his stepdad. At five years old (his bio-dad and I divorced when he was two), my son lets me know how happy he is that I'm so happy now. We have a lot more fun, and I'm able to be there for him a lot more than when I was miserable and in a toxic relationship. I am able to live a more fulfilled life and, in turn, can now give my best to my son.
As for what is the most greedy -- I guess that depends on the individual situation. Most of the time, it's far easier to stay in a bad situation than it is to take the steps to live a healthy life. Knowing how detrimental my last relationship was to my son was the extra boost I needed to stop just trying to put up with everything...I can choose to sit and suffer, but I finally realized that I couldn't make that choice for him too.