This is a spiritual thing.
Perhaps she thinks you drove him away, and she was hurt by the divorce, so having sex wtih her stepfather was a way to get back at you.
You said you have fancied your stepfather since you were 12, so it sounds like you were acting out a fantasy.
Actress British actress Emilia Clarke was born in London and grew up in Oxfordshire, England.
Do not let some pervert come between u and your mom.