This is so heartbreaking to hear BillieJo, I am sorry for your situation. The police can be thugs sometimes and it sounds like they were in this case if they said they would only testify for your ex's brother. They will also lie about what the legal actions may be to scare you off, it's an old tactic of crooked cops. Best if you can document the bruises and damage to your eyeglasses. Next time go to a hospital and get it documented if possible. You will need a lawyer to deal with this and sooner is better than later. I suggest contacting a local LGBT support group and see if they have a legal rep to help you, they may have a volunteer lawyer. You do want to get a legal restraining order if possible to keep that a'hole ex-brother in law away from you and your kids. Even if you don't think he will stay away you need to go through the legal steps when these things happen.
Best of luck and my thoughts are with you,
Hugs,
Stephanie