He's giving awful mixed signals...advice?

That sucks, I think everyone at one point in there life has ventured into the dreaded "Friend Zone", and think that is were you are right now. The guy still has feelings for his ex and those feeling are more developed than the ones he has for you because they are older. Bide your time, she was his ex for a reason, she might become his ex again in the near future. hang in there.