What you describe is certainly erratic and frightening behavior, but personally, I would want to know much more information before drawing any absolute conclusions from it.

Some people do cheat on their partners and when this fact is discovered, they will go to great lengths to distance themselves from their own shame and responsibility, typically, by blaming their partner. Often, criticism is made of the sexual relationship (i.e., you don't meet my needs) but if the partner has previously received a diagnosis of "mental illness" that can be used as a convenient scapegoat. The individual involved in the adulterous affair can claim that their partner is "crazy". They didn't create that web profile -- their partner did! They didn't meet with that woman -- their partner is insanely jealous! I recall hearing of one man whose wife walked into their home to discover him in their bed with another woman -- he tried to convince her she was suffering from "delusions" and needed to be medicated.

A great many injustices and brutalities unfold on a daily basis in this world, some of them between husbands and wives. But the vast majority of individuals involved in those acts have never received a diagnosis of bi-polar disorder or schizophrenia. I suggest you base your expectations of your relationship on your relationship. If it has been stable, equitable, respectful, loving... that's probably a very good indication that it's likely to continue in that vein.