Confused, Depressed

So, I was just told by someone who I've known and trusted since kindergarden, that I'm the reason that I got cheated on in my first in second relationships. Hello again, mental breakdowns! God, I finally started getting over thoughts like that then they were said to my face by someone I never even told I had them. I was also told that my current relationship was a lie and that I wasn't really loved by him. That just killed me inside that she said that. I don't know what to think or who to trust now.