Hi adorning!
First of all, I hope the best for you and your partner.
I'm very sorry to hear about your partner's ordeal. To go through that as a child, I can't even imagine. I was in an abusive relationship before I met my husband. I trusted hubby, but it took me a long time before I was really comfortable being intimate. And I still get nervous sometimes or feeling insecure. But it does get better.
What helped me the most was seeing hubby stop and back away when I said "no". He didn't complain about it and he didn't pressure me afterwards. What also helped was cuddling or getting a massage without it leading to anything sexual. And him showering me with attention didn't hurt either.