The best revenge spell I ever did was one designed to give karma a little, shall we say, encouragement. Many people believe in karma. If they really did do the things you say, they probably deserve to get what's coming to them.
Find yourself a time when you can be alone. You can do this ritual with sea salt or just do it without anything at all. Find a peaceful place and sit, somewhere you will not be interrupted. Center, ground and shield yourself before doing this. Sit and clear your mind. If you're using salt, cast a circle of salt around wherever you are sitting. Now focus on the person/people who wronged you. If you have something of theirs that you can use to focus the ritual, just keep it on you or place it in front of you and look at it. The important part is you visualize the person in as perfect detail as you can. Channel all your energy, including the pain and sadness you feel from what they did to you into the knowledge that they will get what they have done back ninefold rather than threefold. You can write a chant if you wish. I never bothered. The important part is the visualization, so do whatever helps you with that. You need to absolutely know that the horrors they inflicted on you are headed their way in some way or another. Once the spell is done, it may take some time to take effect. Give it a month or two. I got results in about 2 weeks.
This spell works. Please be careful. You may cause harm with this. Only do this if you are comfortable with that fact.