First Serious Breakup....Need Advice

me & this guy i really loved broke up because i accused him of cheating on me a lot because i have trust issues from being so hurt in the past. him & this girl that WAS my best friend got closer to him (she’d go to his job, ft him everyday, & etc.) so me & him got rocky & he claimed he never cheated & i believe him now because me & her had a conversation abt him & she’s just being a supportive friend (she was never like that for me or other people so i found it kinda hard to believe now but i’m rly bipolar about the situation) theres some hours i feel great & others i get reminded of him & wanna breakdown. this breakup is making my depression worse & i need help because no one has the patience to deal w me & keep giving me the same advice & it’s hard to try to go through w their advice. can someone pls help😣.