In the present facts you cannot take legal action against your boyfriend. You have no evidence to prove sexual harassment. For the filing of FIR you must have evidence to prove that he has committed a cognisable offence. Current facts of your case don’t suggest that he has committed any offence.
You both have attained the age of majority. The sexual or bodily relationship has been established by the mutual consent. There is no evidence that your boyfriend has committed sexual harassment by force, cheating or playing deception. Hence, you cannot initiate legal action against him for rape or sexual harassment. You have no evidence to prove that your boyfriend is torturing and harassed you sexually.