I think the way you go about this really depends on how you truly feel about him. My ex did something like this before, and I stood by broken-hearted for 3 months while she was with someone else. But I was willing to be with her after that even though she knew I wanted her in the first place, and we ended up really falling in love. Mind you she is my ex, but we were together for almost 4 years and had an unbelievable relationship for the first 3. So you never really know. But everyone else looks at this like you'd be wasting your time, and they may be right.