Thanks for posting here. I think you'll find a lot of helpful people here. I would recommend therapy for you. You seem well-grounded, and straightforward, but I'm a HUGE fan of therapy.
As a survivor of abuse, let me tell you that it's very easy for us to use our abuse as a manipulative tool. The timing of your partner's admission of abuse seems messed up to me. He had just hurt you BAD. You were expressing your anger/fear/pain/passion. He may have used his abuse to one-up you, so to speak. To derail your expression of feelings and get the relationship back into the comfort of dysfunction, if you catch my drift.
Survivors of abuse, or at least survivors like me, find a strange comfort in layers of lies and secrecy. I call it a strange comfort, because it's anything but comforting, but it allows us to hide our shame and humiliation and pain from ourselves, or something. But this tendency has real-world consequences. It hurts people. It's unsafe. It's unhealthy. It's mean. It's ridiculous. It's a waster of time and money. It builds barriers between people who should simply love each other. It kills intimacy. It carries on the cycle of abuse.
Your partner has all the signs of someone who's not dealing at all with his history. He has no boundaries to speak of. And yet he has an enormous boundary between you (and probably everyone) and his innermost self, his scared and odd little childhood stuck deep down in his being. I say that because lying is a kind of boundary. It shields us from the truth. And he's clearly lying constantly to himself and you and probably just about everyone.
Good luck. He's lucky to have someone with such clear communication in his life. Keep healing. Set absolute boundaries for yourself and very clear expectations for him. He's hurting you, and there is NO EXCUSE at all for that kind of behavior. This isn't about "forgiveness." That's different. You will either forgive him or not. I don't think you're anywhere near that question. The issue here is whether you will have a functional life with him or leave him to his dysfunctions alone. That's HIS CHOICE. Not yours. Your choice is whether you will be functional or dysfunctional. None of these are value judgments. I wish you all the best. Please post and keep us updated. I think it'll be helpful for you, and I can tell you that it'll be helpful for me, and probably for the rest of us.
Once again, good luck. Seek peace. Do fun stuff, so you don't wallow in the pain of it all.