I didn't read every reply except for Ravvenn's. Are you going to be able to keep him out for good since he busted your lip? I hope so!
The laws vary from state to state but....
If he returns, you can always Baker Act him if he threatens to kill himself again. It's simply your word against his and no proof is needed. You call the cops and tell them he threatened to kill himself and they will immediately involuntarily commit him to a mental institution and immediately perform a drug test. The problem? He can manipulate his way to convincing them he isn't crazy. It will at least get him out of your house for a couple hours (probably longer -- usually 24 hours or longer unless he masterfully manipulates them), possibly enough time to get your stuff packed up.
Where I live, I dealt with a similar, fucked up situation with a family member and thankfully, I got him to leave voluntarily (he then proceeded to threaten to destroy my family, my career, my life, etc.). In reality, just letting him live with me for a couple months (even with no lease or paid rent) meant he was a legal resident of my home and I must serve him a 30 day eviction notice or he can come back whenever he wants. The only way around that is to get a temporary restraining order and then make it permanent, which I thankfully did not have to do. A domestic restraining order is just a piece of paper and can enrage crazies further, however, you don't need a lawyer to get one. You simply go to your local, county court and ask to speak to the Clerk of the Court and they'll give you paperwork. Google "restraining order <state name>" for appropriate info. In my state, it's free to file. In some states, it may be $20. They will then serve him, which will immediately kick him out and give him a court date without needing an eviction notice. Once the court date arrives, you speak to a judge and the judge decides whether to make it permanent or not. Since a child is involved, the judge will probably side with you but that's not guaranteed. It may not be made permanent but it can get him out of your hair usually for a couple weeks. If he shows up, call the cops and they immediately arrest him.
If he is allowed to come back (I hope not since he busted your lip), I would baker act him if he threatens his life again, give him a 30 day eviction notice once the cops show up, move your shit out immediately before he returns (plan ahead!), go to an apartment, and put your home up for sale and never look back. He may destroy your home once he returns from the baker act since he has 30 days to evict but that's a small price to pay for your long term freedom and sanity. Your brother and mom sound like classic sociopaths and they have preyed on your kindness and good will. I would cut them out of your life and never look back...especially for your child's sake. Don't feel guilty! You've done nothing wrong! In fact, you have been a wonderful person and tried everything but enough is enough. Don't feel any regret or guilt! What your Mom did to you is downright shameful and pathetic.
Concerning the pawn shop, they can't sell stolen shit. It may be too late now since you are already making payments but you can always demand the stolen items back. If they refuse, you can tell them you are reporting it to the police since the pawn shop is breaking the law.
How much more money do you need before you can move out? I'm sure some people on this board would be willing to send you some money over paypal. Professional movers are usually only $200-$400 bucks to move out your stuff (so you can get your stuff out immediately if you decide to baker act him) and could help you get it out quickly. If you have to leave anything behind, he may destroy it but at a later time, the cops can monitor you while you move out any remaining stuff...at least that's how it works in my state. The fact he busted your lip should give you a lot of leverage and leeway. In fact, since he physically harmed you and it is documented, a judge is much more likely to grant you a permanent restraining order.
Hope everything works out the best for you and your child! Feel free to respond on the board or pm me if you want to talk further.
