Im not that sexual but I am

Okay, let me explain. So I am the most sexual asexual person you will probably ever meet . I joke around alot but constantly apologize . I've had "trauma" I guess in the past. My first time was with my ex. He was super sweet and gentle about it but I had a major I don't know panic/ anxiety attack afterwards. Shaking, getting sick, trembling, crying good it was horrible. It wasn't his fault but we ended up breaking up anyways. What do I do?! I'm afraid I'll never be able to have sex with my partner without having one of these episodes afterward.