How does one go about doing this?

Ok, I know that seems like a simple answer "you just do". And it's true, I do. I didn't mean to fall in love in this case, not at all. By the time I realized that there was an "issue" I was already too far gone. It happened fast and hard for me. I'm really struggling with it because I don't really want to "let go" but a big part of me tells me I should (and everything I've read on the internet).

To be clear, he hasn't (that I'm aware of) been formally diagnosed with NPD (Narcissistic Personality Disorder) so I can't swear that he has it. That said, I'm almost positive that he does. I know that I'm not licensed to diagnose someone with such things, but his personality traits meets almost every single one of the traits that come along with NPD, as a matter of fact- I was somewhat relieved when I read the articles I read (mostly in psychology publications) because I was starting to think I was going out of my mind. It felt like he was REALLY playing "games" with me and I couldn't decide why he tells me he cares, but acts another way.

Basically, my question is this: If I do suspect he has NPD and I know I can't change him...is there anyway I can stick around anyway? Or should I run for the hills? (please note, it's too early in our relationship for me to mention this to him or suggest he get some help.)

Please don't think I'm bashing anyone who has this disorder. I am sympathetic/empathetic to anyone who has ANY kind of struggle. I have plenty of my own, but I also have to look out for myself and my own sanity.

Any input or advice?