See a dermatologist for your psoriasis, there are lots of different schedules of treatment for this disease of the skin.
Stress has alot to do with it but it is able to be handled. Don't suffer with it unnecessarily.
Your mother and that man she married... that individual ruined your childhood. Your mother was in some kind of denial as she never would have discussed him with your husband if she was in her right mind.
No matter what happened, the bottom line is this... you do not have to allow your mothers inaction, or lack of things she did afterwards, or whether she used words or had intentions, to decide the rest of your life.
Do not let this illness of attachment to a pedophile finish the job on you the rest of your life.
Listen, your mother did not win any medals in her life for overcoming a test or defeating an illness.
You still can. You do not have to remain a victim, or feel sorry, a past, thru guilt because your mother couldn't become repulsed by a pedophile. Period.
She doesn't get to rent space in your brain one single day more. Nor your husbands.
She was your mother, and for that, you love her.
Other than that...nothing. You do not owe her any more thoughts regarding her husband or her twisted lovelife.
That's my thoughts.
Peace to you.
With Support and Good Will,
night
:hug