what's going to happen to him?

So I just found out my ex highschool sweetheart landed himself in jail due to arson. Complete story in pictures from his mother. I'm thinking the details are probably going to matter. This news brings me so much grief because i didn't know he was that bad off and now I'm scared for him. Does anyone know how he might be charged in the long run? A quick google answer was 3-5 years in prison!! 😳But he's mentally ill so does that change anything? I can't handle googling this without crying and I know some of you ladies love research and some of you know the laws so I was hoping you could help me. I live in CA.