Family Issues Support Group
Family issues is a huge range that go from minor conflict to major misbehaviour and even abuse on the part of individual members of the family occur. Whether you feel you are in a dysfunctional family or you're dealing with a very specific issue, this is the place to talk about it and find others who might be going through the same thing.

Do you have a formal custody agreement with his father? the trash talk needs to stop, it will not remotely help your son adjust. It seems to me that his abuse would be grounds to severely limit visitation if not outright discontinue it. Maybe it would be possible to get a mediator of some kind involved to establish ground rules for visits.
One of the biggest things that has helped me to bond more with my son is finding activities we can enjoy together. We go for walks, we just redecorated his room based on the solar system, we wrestle around. We watch nature shows and the discovery channel and he has a great time telling me about all of the animals. In short, we try to do things together that could be termed "quality time," as opposed to buying him every big shiny new toy as his father does. I hope this helps.
I wish you the best.
Good luck and God Bless
I agree with those that have suggested counseling and I think both of you would benefit from that counseling.
Your son is feeling the fact that you are disliking him - that cannot be hidden and kids are very in tune with our feelings. I would get into therapy just as soon as possible.
Good Luck =]