<human>: Give me the gist of the text in a nutshell

When my son was 4 months old, I left his father because he was an abusive asshole and didn't help out with the baby at all. 
Ever since I left he hasn't really put any effort into seeing our son unless its convenient for him, and our son will be two next month. I gave him an ultimatum and told him he either has to make a consistent schedule will our son or just stay away because it's not fair to him. He tells me that I'm being irrational and difficult.
Last time he saw our son was a couple days after Xmas, he took him out bought him some toys then brought him back and I didn't hear from him again until just the other night. 
He's saying that he wants to be a part of our kid's life and saying that his schedule is the same till August and is willing to make a routine with our son but it's going to change after that. (Sounds promising..)

Am I wrong for not wanting to let him see our son? My whole worry is this will maybe work out for a bit and he will just go MIA again, and just as our son is getting to know him he disappears. I really don't know what to do right now. 

He doesn't pay child support either.
<bot>: my son's father isn't really around and randomly wants to be in my son's life more, but am I wrong for not even wanting to give him that chance?