I think I'm losing my mind! What can I do to keep my mind healthy?

That depends. If it is a relationship problem, go see a psychotherapist. If it is something else, see a psychiatrist. It could be an anxiety disorder, mood disorder, thought disorder, or any type of "chemical imbalance" of the brain...
Losing mind. You should make an appointment with your doctor to discuss your feelings and get an examination as there are several illnesses that can cause one to feel as if they are losing their mind, and often treatment can be of great value.