Get out there mate, that shit is toxic as all hell. She is just taking from you emotionally, and when something doesn't go her way she goddamn slaps you. 4 times at that! First off you need to get out away from that literal abuse, You didn't even defend yourself, that is her grinding you down and abusing you.
So let me play it straight, not the high road, not the low road, the path that gets you out and better ASAP. Do you have family (first choice) or friends (second choice) you can move in with or at least stay with for a while. If you do, move in them first thing. Take your most valuable things with you in case she rages and breaks things. Does she live with you, is she on the rent officially? If the answer is no to living then lock the place up go to family/friends and get them to change the locks. If she lives with you pays rent but isn't on the lease, well tough shit she can settle in the court (good luck on her proving it). Kick her our or get a friend to kick her out with you.
File a police report, do it and get her attacking you on the record, sure it might be a pain but trust me you'll want that, regardless of if police investigate or the DA presses charges.
Step 1:
Get out/get away (NOW, DO IT, CALL A FRIEND OR FAMILY, FUCK THE HOUR, JUST DO IT) It might seem dramatic but you need to get out now to the rest.
Step 2:
Report her to the police, I'm serious, I don't care she is a women and you don't seem to consider it assault. call them and tell you want to report assault and domestic abuse. DO IT. It will only help you from here.
Step 3:
Get her out of your life forever, move out, kick her out, block her on media, break up and stay broken up. You seem vulnerable and unsure here, put on a scary mask and go public, use social media, tell people she assaulted you on facebook, and mocked you when your mother died. She is a terrible person so let everyone know she is terrible. This helps you out in two ways. First off you just burn and salt that earth, no moments of weakness going back to her now. It gets all friends and family on your side. get any stuff or your possessions from her too have family or friends there.
Step 3.5:
(Break up with her, but the text below makes you feel the least bit vindicated consider getting some well earned catharsis from this break up. To everyone else, I know its overtop, but OP is abused and emotionally numb, its time to wake him up.)
This part might hurt or it might be catharsis but you need, and don't downvote, I'm its classless. Break up with her OP, do it on the phone or online it doesn't matter what matter is you're getting out and getting away for her terrible (litteraly) abusive self. Turn everything you liked about her into the nagging and endless demands, that contempt she had for when she slapped you (she always feels that way, you know).
Well its time to get mean and get control back. Use only words here, while you're breaking up make this cut clean, cut that tumor out. Every mean thing you can think of slam it on her, every weakness and fault, every time she depended on you (was weak) throw it in her face. Be savage and cruel, in short do you best to break her spirit and her standing (remember you told everyone she was abusive and cruel, poof goes her support network too). Crush her and get the catharsis back, you don't let someone assaulted you and leave them with a polite little break up, you walk away proud as she is drowning in shame and that abusive neediness.
Step 4:
You never talk to her again, don't be the guy to shit talk your ex either, you're already won that fight. Clean break, never talk to her again. Cooperate with police if they investigate the domestica abuse.
Step 5:
You ready? Breathe deep...ok its time to process the loss of your mom, this woman, your GF is keeping you from being able to process and honor the memory and passing of you mom. When she is gone then you'll finally be able to feel. You're going to get the support from others you need, and move on from this.