Nothing feels better than REVENGE. Don’t get mad. Get even!

How sweet was that revenge?

Even though it's very tempting to ascribe to that saying, but I think a better one-- if possible-- is to  lose the person, their name on Social media,  phone number, address  and email id, or make yourself scarce to the point of oblivion.  Getting even can be a high energy project that is too consuming of your own mental and physical resources to make it worthwhile.  What with high BP, I wouldn't recommend getting too intense about revenge.  Consider cutting your losses and move to where you are free from this association, like a Caribbean Island.

Aren't you happier here in the Caribbean?

    However  If you still care  about the person, you could try to do what Jesus would do, and turn good for evil in the hopes of turning the person around to a better life, showing them the way unless he/she is already over the edge.   Just wave....

Your sense of betrayal will fade if you let it go and don't keep reminding yourself of it; you can find solace in being the better person and realizing you are by not continuing the cycle of hurting and being hurt.  The immediacy of the betrayal is still driving your feelings, but it will dissipate.  It is hard to read your story without wondering what drove the person to do this;  it is hard to believe there wasn't something or some provocation that caused this concerted effort.  You might reflect on that a bit more before taking any actions in order to understand why what happened.  Getting even might just create another round of revenge you wouldn't want to deal with. The Best revenge may be becoming friends with some new folks who just like hanging out with you and enjoy your company!