It's difficult to blame people for their mental illness, but the damage they do as a result of their actions is real, and while you can forgive you should never forget.

I got romantically and sexually involved with a person who had schizophrenia, they would occasionally make very wild and inaccurate accusations toward me, and when I broke it off they began stalking my friends, family, and me. At some point, the episode they were having ended and they stopped, and later, she said they forgave me for what I did (which was nothing).

While I sympathize that some of the emotions they were feeling were out of their control, the act of buying airplane tickets, renting cars, and harassing friends, family of mine, and me IRL was over the top and frankly, imo, unforgivable even with a diagnosis of mental illness.