When he uses guilt, into getting you to stay, its manipulation. deeply suicidal people, tend to not talk about it.
There's something about the psyche of a sex offender. My father, used to teach in a prison, for a couple of years. The percentage of rehabilitation for sex offenders, is marginal, at best. least respected segment behind prison walls, fyi............
18 years of one's life, is a long time to devote to someone. Your posting sounds more 'caregiving' than partnership.
It's tough when loyalties to another are strong. Placing you in an emotional worrying about him state, that isn't fair to you. You deserve better.