I don't think you've an Obligation. However if you do WANT to tell him (not out of fear, guilt or obligation) because you think it'll help, then go for it.

I haven't endured the medical traumas (they are horrifying and it's obvious why they're traumatic) and possible molests you have but have physical intimacy issues from a single incident trauma. In my case, I told my commited partner because I wanted to explain my bedroom issues, and because for me we'd reached that level of trust and intimacy where I felt it was safe to.

Whatever you decide, I hope you know you're entitled to privacy and you don't have to share anything you don't want to.