In bed with dad

In a morning when mum has gone out for her early shift one day a week, I usually get in bed with my dad for a hour before I get up for work its something I have always done, I only have my nightie on, when I slide down and my nightie ends around my waste with my bottom in dads lap, he always had his pyjamas on the last time he didn't so my bare bottom was against his naked groin I could feel his body hair and his penis against the crack of my bottom, I know he couldent help getting an erection he apologised, said it was involuntary and he couldent help it, it felt wrong and good at the same time having his dick resting in my crack, if anybody can anybody understands that, we didn't do anything naughty, is it really bad of me enjoying his penis pressing on my private part, it did have the desired affect, if I get in with him again am I asking for something to happen, I know he is going short of sex may be that's why he excited about my bottom in his lap, should I or shouldn't I want to and don't, Help