Most Helpful Guy
1. I wouldn't do that.
2. If I did date someone else to make her jealous I would pick a girl that had qualities I knew my ex wish she had.
If my ex wish she could pull off dark hair, wasn't so pale, had bigger boobs and brown eyes I would then go out of my way to date a big breasted latina or greek woman who tans well. I'd take her on special plans my ex and I made, but never did as well as rewrite memories I had with my ex and take pictures to put on social media. If you're going to do something, then DO it!
Most Helpful Girl
No. That's way more likely to backfire and just make your desperation painfully obvious.