Relationship Advice

How can I stop being so negative, I’m constantly thinking about “what if”; “what if they’re cheating” “what if they’re talking to someone else”etc…. It’s exhausting and it’s making me miserable, after being in a relationship for 8 years and getting done wrong it made it hard for my current relationship I don’t want to be miserable someone help!!! What can I do to rewire my mind into being more positive and to stop thinking like that?