You need to think about the consequences of your fantasy, because your mother is not going to comply with your fantasies, unless she is a sex-addict, drug addict, or both of these. Perhaps if you would draw a picture or cartoon of what you are imagining you might get it out of your system.
perhaps you could do that. Are you a Bill Cosby wannabee? You're abusing the anonymity of this website to air rape fantasies. Masturbation is a victimless pleasure.