Confused..

Am I wrong to keep my son to from his "dad" even though he hasn't been here through the pregnancy at all, he hasn't bought anything for my son and he already has a child he doesn't do for & rarely sees. I want my son to have his dad but I don't want my son to be played with and his feelings hurt, I don't want him to think he can only be a father sometimes I know it hurts the baby more keeping them from a parent but it's also going to hurt him to only see his dad sometimes. That's not healthy for a child. He already has a child he should know how to be a dad & I can't keep giving him chances when he messes up but then he makes me look like the bad person and makes it seem like I keep my child away because we're not together & he has another girl which is not the case but I also don't want my son around his girl  because the time he has with his son is for him to spend time with him, & I don't even know the girl because it's always a different one.