I personally wouldn't ignore him that is really not a nice thing to do. I've ignored several of my ex girlfriends in the past and have come to realize it's wrong. If you treat him no different than you treat everyone else that alone should be enough.
Just broke up with my girlfriend the other night cause she has all these issues she needs to deal with before she can be in relationship. Tonight 2 psycho ex- girlfriends call me up wanting to hang out so I told one no and hung up on the other one. Life sucks.