Long story short, I left my ex-wife because she was abusive and controlling. I came back for 4 months, but it was more of the same. Moreover, the children clearly disrespect me (i.e., referring to me as a "half-adult", checking with Mom after I say anything, and so on). She told them (before I agreed to it) that I was returning over my Christmas break. There's no way in hell that I'm doing that. I hate myself when I'm around her. I pay for everything and yet I can't do anything (not even drink a can of soda). Anyway, she has their hopes up, but I'm not going to return. It's not my children's fault, but I dislike my interactions with them as well (e.g., if I try to get them to do something they'll scream no and get "backed up" by mom; at one point, my son bit me on the leg hard and then cried to and was consoled by mother because I held his face so he had to look at me while I told him never to bite anyone). At present--to spare the children's feelings--I'm just going to say that I can't afford to visit. Then, in private, I'll explain to the ex-wife that I'll need to rent a separate place if I visit. There's so much more I could go into, but that's it in a nutshell.

tl;dr: Ex-wife is a controlling monster and sculpted children in her image. What do?