In the game you father gets married to a women that women convinces you to leave town or she will tell the cops you had something to do with your friend death then your father dies so you come back for the will reading
This game fits perfectly into short description you gave with one exception that she is not MC stepmom because she never married MC's father and was only just his girlfriend.
And yes she has three daughters with whom MC was very close before he was forced to leave by her but you didn't write anything about any girls.