Welcome to wiki, I hope you will find some answers.
Are you aware of mediation services?
I think if you Google it you should be able to find a local place. They basically have a trained impartial person sit you both down.
And what about counselling? Your post is all about your ex being abusive and calling the shots. Do you actually want to end your marriage and split the home? I realise that you have done the right thing for yourself and your boy but I kind of hope that she has gone hormonal mental and that you may sort this before going down the crappy divorce route. I believe that mediation can get the whole divorce thing rolling but you 2 will be face to face instead of paying 2 go between expensive solicitors.
In answer to one question I do believe that she absolutely cannot change your daughters name without your consent. Google the question to be sure.