I broke my brain

As I was waiting for my appointment in the large open waiting room, an older man in a wheelchair came up to me and we started talking. He said I look too young and healthy to need physio but I told him I actually have a brain tumor and need help with my balance. He apologized for assuming I was fine, and that was ok with me. We started talking about being disabled and I thought to myself, "this is great. I finally get to speak with someone irl who understands what it's like living with a disability". He gave me a friendly pat on the arm once but it was fine, nothing nefarious and it didn't bother me.

All was good and the conversation was polite but then, because I was wearing a mask, he said leaning in close to me, "why don't you take that mask off so I can see that pretty little face of yours" and he began stroking my shoulder and my upper arm slowly. Now, I'm terrible in situations like this because I'm polite and don't want to provoke things further or cause things to escalate so I said, "I'm recovering from an illness and wouldn't want to pass it onto you". He then kept touching me and said, "I'll take my chances, it's worth it to see your beautiful face". His groping didn't stop. I told him that I was going to keep it on and eventually he backed away and luckily I was called in for my appointment.

I know i should have handled this situation differently but I froze. I was also really disappointed as there was another man a few feet away from me who witnessed it all and didn't say anything, plus a female receptionist. I'm also sad because I don't get out much and when I finally got to speak with someone who I could relate to, this happened.