I agree to this, seems like bestie is more than bestie, but it’s all speculation from my end from what I am reading here,
If possible hire private detective start collective evidence, once you have enough evidence to build case ( definitely consulate a lawyer since he will know better what is enough )
Hire a lawyer get expert advise, before it’s to late and you have to deal with IPC498A, as you have already mentioned that her family is accusing you of sexual harassment.
Times are like this difficult and every steps you take, you must take legal advise from expert and move forward with it.
You will be better off, if you get out of this relationship which I don’t think has any meaning.
It’s just my opinion.