As stated before this is a multi-state forum and as such it’s hard to say what the laws are in other states BUT in Texas (my state) she was well with in her rights to protect herself and child against a sexual predator. To say all he is going to do is sit there and pleasure himself is a guess and might be a fatal mistake. a sexual assault does not have to employ physical contact but can be a verbal and visual
PC §9.32. DEADLY FORCE IN DEFENSE OF PERSON.
(B) to prevent the other's imminent commission of aggravated kidnapping, murder, sexual assault, aggravated sexual assault, robbery, or aggravated robbery.