Old man has expressed that he wants nothing to do with your boyfriend. Why not respect those feelings. He isn't telling you that you can not see your boyfriend just that he wants no interaction with him.
This is exactly what I'm up against too, @primalcupcakes. I do not fantasize that my husband will ever evolve into a guy who would accept another lover into our home or daily life. I'd be happy if I knew he'd tolerate at least a friendly acquaintance-ship with anyone who was truly important to me. Maybe someday he'll get to that point. For now, I'm just so grateful that he's come as far as he has, as quickly as he has, out of his love for me, and I try to honor to his request for zero interaction/affect with my love interests as much as possible. But I worry if I were to get serious with someone, keeping hubby completely away from it of would prove difficult.