bf and his sexual trauma

I started dating this guy recently. The first time we had sex, he was willing to do whatever with me, but he couldn't stay hard. then the second time we didn't even try half the things we did ar first, and he couldn't stay hard again. Fast forward a few weeks, he opened up to me last night about some things. I told him it was frustrating to want so badly to be with him, and how I was willing to try whatever, toys, if that would help him stay hard. He then explained to me he experienced sexual trauma as a child. He thinks from possibly his mom, dad and uncle. But he can't remember. He just thinks it happened. And now, he feels like his penis is going to be ripped off if he has sex with me. I just don't know what to do. It's confusing how before he was willing and now as we've gotten closer and know more about eachother, now he's not willing to try at all. I asked him last night if us masturbating together but on our own may be a way to try easing in. That way there isn't a physically stimulated fear by me. Or just me touching myself and him watch. I went through a lot of sexual trauma as a kid too. But I've worked on it for many years, and I was lucky to enough to have a friend give me almost like sexual therapy. It was so freeing. I tried explaining that to him, but he's so ashamed. We got into a little argument last night about it, and I ended up going home at 3am. I just was upset with myself and felt I upset him enough too. Any recommendations from people with experience ?