Hello Disconnective,
I see its your first post so welcome ... .this is a great place with others like yourself have shared stories or are or have been going through what you are. I would encourage you to read all the reference material on the right & at the top of the page. Here you'll find no judgement from anyone ... .just a helping hand to assist you ... .we can't walk the path for you ... .but we can give you the encouragement you need to find a better place.
I would seriously encourage you to see out professional therapist to help you sort through your thoughts, feelings, and the anxiety you're going through. It's not a sign of weakness but as I've personally have found a great source of personal strength. I would encourage you to really do some soul searching, self evaluation, looking inward to learn about yourself. Most of us here are in some way shape or form a codependent ... .who want to save & or protect others and someone with BPD is the perfect match for those who are codependent. I would suggest a book called, "The Human Magnet Syndrome", you should be able to find it at your local library or order it online. It will educate you on how these two people on opposite ends of the behavioral spectrum are perfect for each other ... .HOWEVER it will be a crazy train roller coaster ride that is not like any other you've been on. And I can see just from this one post of yours is a Disneyland E ticket ride crazy train.
You said, "I've accepted it's over, but I really want to feel like it's over and move on. I know I've been through something damaging, and I'm worried I won't heal properly." All the more reason to seek out professional help ... .to help you sort through what you've been through and heal properly. I would also encourage you to seek out some professional help for your son to help him sort out what he's thinking, feeling & learn about what good relationships are about.
If you want it to be over the first step is to go No Contact (NC) in order to start the healing of yourself & your son. I would block her number on your cell phone so you don't get woke up in the middle of the night or constantly harassed. Again ... .myself or anyone else is NOT judging ... .but what made you think that a relationship of any sort with a lesbian would work out and knowing she was an alcoholic? Of course she said you were her savior ... .its what BPD's do ... .it feeds what a codependent needs at their core. She feeds you ... .you feed her and it goes around and around.
BPD does a push / pull thing ... .they have an extreme fear of abandonment ... .so she begs you to stay ... .move where she is ... .or she moves where you are ... .then once that happens ... .they have the opposite feelings ... .they have a fear of engulfment ... .so they push you away ... .you've describe classic push/pull behavior although at what some would see as extreme. There is a book that describes this too ... ."I hate you ... .Don't leave me" ... .read it ... .you'll be amazed at the similarities.
BPD also thrive on drama or crises ... .DO NOT LET HER FLYING MONKEY'S BE YOUR FLYING MONKEY'S! What ever her crisis is ... .it's her crisis ... .ITS NOT YOURS! Don't let it become yours. If you block her number & text then it'll help with this.
Physical abuse is also common with those who suffer BPD in addition to emotional abuse, mental abuse, & sexual abuse ... .it's a means to control you and or the situation.

Obvious hitting you with the bat is physical abuse in addition to countless assaults.

You referenced the sexual abuse, "Sex issues because she's a lesbian. I didn't don't do this and that right." This is a way to belittle you and to make you feel less adequate in an intimate situation. Take away your manhood.

Your reference to mental abuse, "The lies, the drinking, drugs, the money spent, the fast food, the complete destruction of my life."

The threats, the hitting, the venomous guilt trips and name calling, All of these are red flags in a relationship that isn't in a healthy state.
She hasn't contact you in 10 days ... .it's not a matter of if she will but WHEN she will reach out to you yet again because of a crises that only you can help with.

Are you seeing a pattern here yet Dsisonnective? Her flying monkey's will be set lose again to cause havoc & only you will be able to put them all back in their cage. Another reason to block her number on your phone.
You have a lot of healing to do from your post ... .come back as often as you need to ... .as often as you WANT to. This sight is just another tool to help you on the road to a full recovery of being in a relationship with someone who is BPD ... .if that is what you really want? Read, educate, learn and live your life!
JQ