It is quite a usual reaction after a break up, to constantly think of ways to get back together with your ex, and, no matter how hurt and angry you are, making your ex jealous is definitely not the way to go about it.
Yes, you are suffering terribly after your relationship fell apart, and yes you feel that you cannot go through life without him/her, but using another person to try and get your ex back is not only unfair to the unsuspecting third person, but is a sure way to push your ex even further away from you.
You must remember that your ex probably broke up with you because of something you said or did, and the sensible thing to do is to work on correcting these mistakes you made that caused the relationship to fall apart.
Instead of using another person to try making your ex jealous, do something that will give you a better chance to get back together with your ex - something positive, rather than something totally negative.
In other words, admit to yourself that you are to blame for the break up.
Accept that you and your ex need time to get over the hurt and anger before you can make contact with him/her, in a positive, mature manner, without using someone else who will no doubt be hurt in the process as well.
Making your ex jealous is really not necessary.
It would be a much better option to try and improve yourself as a person, and show your ex that you are willing to change.
This will give you a very much better chance to get back together with your ex.
The idea of being with someone who is willing to co-operate for the sake of the relationship, is much more attractive that someone who behaves like a spoiled brat, in order to get his/her way.
Be mature about your situation, and deal with it in an adult manner.