You should write him..
You and him have been friends for awhile, and that time is all for nothing if you just forget about him.
You and him are friends...Friends don't just forget about eachother..
Even if you feel bad about it, it's still horrible to just let him rot with no word from you...

Other then that, Trinia is a bitch, and needs to learn that you're a friend of his, whether she agrees with it or not.