Several years ago at my apartment, I woke up at 3am and felt something around my neck squeezing the life out of me. I gasped for 10 seconds then it stopped. Never saw anything though. For a whole I would wake up in cold sweats at 3am as if someone was torturing me. I would get nightmares and they would come true, all the time. I broke up with my girlfriend right before this happened, which leads me to believe she did something, like magic. Because as long as I have been alive I don't believe in this, but this kind of thing only happened when we broke up. I never saw her again.
Fast forward 7 years later, I had very bad luck, lost money, got cheated by friends, and was constantly accosted by homeless people or weirdoes that would just pick a fight with me... They just would come out of nowhere and pick a fight, surreal! So I went to our family psychic who is well respected because she doesn't charge money. She said something very mean was following me and she couldn't do anything about it. It was weird because I didn't tell her anything and she just said that.
How do I get rid of a spirit like this, forever and can I do something, like a prayer to find out how it happened or if my ex-girlfriend did something, or what this thing is?