Yes you should talk to him. You don't have to act like everything is wonderful, but you should be as kind and as civil as possible. Keep it about the game if you have to.
If he sits next to you...big deal. Don't give someone that much power over you. Remember the game is about your son and that is his father.
You can be nice for an hour or two. Just don't get sucked into an argument. Be the bigger person. Be there and in a good mood for your kids. It is o so hard to do at times.
