In my own experiences dealing with this issue I would say that you are probably on the losing end of this fight. First, you are both in the adult business, Second, you advertise your site as a resource site which theirs is as well, Third, they have had their domain longer than you have which sets precedence. They may be willing to allow you to keep the domain and not use it for the adult business but it would pretty much be worthless for that. They probably have much deeper pockets than you do and will be more likely to tie it up in court until you can no longer afford to fight.

Harsh realities but I am about 89% certain that i'm right. I'm not an attorney but i've been through two domain disputes. One I pulled the domain even though I felt I may be right and the second I know I am right and not much they can do about it except fight me until i'm out of money.

Just to go a little further I looked at the domain since it's inception. You went from a surfer oriented site to a webmaster oriented site. This signals that you weren't making any money with it as a surfer site and with a message board with no advertisers you aren't making any money it looks like. So, my question to you would be.. is it worth keeping a site that doesn't appear to have a revenue stream