Can i ask for help from a college prof?
As long as you recognize that the prof isn't a mental health professional and don't expect her to go beyond her expertise, it would be fine to ask her for help. Especially if what you want is help in finding a proper therapist. 

Professors (many, at least) try to be helpful and supportive in such situations, even though solutions are beyond them. 

But it is probably a mistake to overload your relationship with her with personal issues. Separating the personal from the professional is normally the right course. 

However, your university may also have an office that provides personal support and might also be helpful in finding a compatible advisor. 

Finally, if sexual abuse is an issue, then you should think about other avenues so that it stops. Again, the university may be able to help if it is related to actions taken there.