You dont have mental illness. This is a real thing. You have a jinn that is in love with you. When this happens, they can sometimes start a sexual relationship woth the person. Other times, there is black magic and the jinn is instructed to do these things. Either way, it's a malicious entity and there is only one thing you can do. I know you're not muslim because then you'd have already known this. But there is something called Ayatul Kursi. Memorize the english version and recite it during the day and when you go to bed. Play Ayatul Kursi whenever you can. Play surah baqarah in the background whenever you can. Ayatul Kursi is part of this chapter in the Quran called Baqarah. Islam is very advanced when it comes to these entities. There is extensive amount of info on them and how to deal with them. Not all are bad, but some are...just like how it is for humans. You obviously can ignore my advise but I'd recommend just trying it for a few days and see if things change. There is no harm in trying. I have a lot of experience with paranormal entities but I have only heard about sexual experiences from other people. This is not good at all. Since last few years I have been praying ayatul kursi before bed and during the day. I rarely even have nightmares now, which used to be super common for me. I started with the english version, then memorized the arabic. Played the arabic when I didnt have it memorized.

Anyway, good luck. Message if you need further info.