Someone on another forum seems to have a crush on me and is convinced I'm the best thing that's ever happened in the world. Of course, I know I'm definately not the best thing that's ever happened, I have the worth of a squashed slug

I like him as a friend but realistically I'm much too damaged to ever be able to try to be anything more than a friend to anyone.

How can I let him down gently if he starts flirting with me again? So far I've ignored his flirty comments and just answered the friendly comments he's been making.