What is it like to go through a custody battle?

My abusive ex girlfriend is threatening to fight me for custody of our son, who is terrified of her.

Details here: http://www.funadvice.com/q/who_would_win_this_custody_battle

I’ve heard that these legal battles can take years and can cost tens of thousands of dollars. That is all I know about them.

How much time do you generally spend in court? (Please answer my other question if you have any idea of who’s more likely to win. I am unspeakably anxious)

Mostly, if you have been involved in a custody battle, what did it feel like? What sort of evidence do I need to provide in order to prove abuse? She had him for 4 and a half years before I knew about him and he is covered in scars.

Who would they actually question about me? My father, my doctor and my psychologist are the only people who I can personally think of.

I will not settle for anything less than full custody. How long can it possibly take me to acquire it?

Where would he stay during the court case? He is not in any danger, here. He’s well adjusted and very happy. Getting him to that point was very difficult and I’d rather not ruin it, now.

Best answer will go to the best description of the experience. I’m hoping to get a few people who have actually been through a custody battle. I want to hear your stories. I’m hoping for as much description as possible.