I was told that lyme meningitis isn't contagious through casual contact. is it contagious through sexual contact or kissing?

No: Lyme disease is not contagious at all. Please be skeptical about the diagnosis. There is a lot of medical literature showing that it is over-diagnosed. Blood tests for it can often be falsely positive, or misinterpreted. Many people claim to be Lyme disease experts. I would trust only a board-certified infectious disease specialist at an academic center to make the rare diagnosis of Lyme in brain.