Should i tell my best friend?

Well for starters my best friend is pregnant. I was over her house spending the night an her baby daddy was there. we was all sleep an i felt some thing touching me so i moved away an scooted then it moved closer an kept touching me. I thought it was her being funny but then it started to try to pull off my pj's and grabbed my bottom. then i grabbed the hand an wasn't her hand it was to big then i glanced over an it was her baby daddy but i was scared to say anything about it because it was his child an i know it would be hard for her to take care of the child her self. An i told him to his face the next day an told him if he ever did it again i would say something to her. And me an her brother goes out so it would be more of a prob;em an it a lot more complicated then just telling her