Welcome, Gotta. I'm glad you're reaching out for support. It kind of sounds like you may already have an idea of what you need / want to do, but maybe kind of want confirmation that doing so is OK. - FWIW, I could be projecting, because I was in a similar situation with AXH, my DS's father. I stayed for so long because I kept moving the line of what I thought I could deal with. "If he does *this* I'll know it's time to leave." Except when he did *this*, I decided, it really wasn't that bad, but if he does *that*, then it'd be OK to leave.
I convinced myself that his abusive behavior was because of his drinking. I waited for him to stop drinking (and using), because then, I thought surely, things would be OK and I wouldn't have to leave. AXH's abusive behavior has absolutely nothing to do with him drinking or using. It's his underlying beliefs/feelings/conceptions about relationships that drives how he treated me, and continues to treat his subsequent GFs. Because we have a son together, I've watched, and am watching from a distance, the same relationship arc play out between him and a couple GFs now. It's eerie to see now that I'm no longer stuck in it.
I know how utterly draining being in that type of relationship is. There is no timeline for when you have to do anything. All you have to do right now is breathe and love your son. It took me several (many) months to be able to leave AXH after I finally realized it was time to go. Part of the reason it took so long was financial; another part of it was that I was just so tired. I did what I could when I could. That's really all any of us can do.
Contacting the National DV Hotline would be safe place to start.
The National Domestic Violence Hotline | 24/7 Confidential Support or 1800-799-7233 or a local DV resource. They won't tell you that you have to do anything right now. If you need to stay for now, they can help you plan that; if you decide to leave, they can help you plan to do that safely, too. Local resources can provide support groups and educational meetings.
Wishing you peace and continued strength. Please take gentle care of yourself.