confused (spoilers)
I just watched the movie tonight and did not read the book. There was one scene of Trixie buying the drugs, and that the mother knew. Was it some kind of sex drug that she gave to Jason? I gained the impression that Trixie set him up for rape charges or to have sex with her. If she gave him a sex drug, then Jason wouldn't be able to stop.
I didn't care for the end of the film - where life goes on, and oh well, this is all part of what parents have to deal with with teenagers.