Should I tell her? Help pls

My best friend and I have been in each other’s lives for as long as I can remember. Our parents have been friends since before we were born.

Our parents were close to the point that my parents actually “adopted” one of my best friends siblings; both families got more integrated that way and we all became a big family, although my family lives in Europe and theirs in Africa.

However there’s something that happened that have been bothering me. We always stay with my best friend’s family whenever we vacation to Africa, and normally my best friend would be there however she was not there the time I went there because travelled abroad for her studies.

I was bored most of time because I didn’t have anyone around my age that I could hang out with but I still enjoyed being around everyone. However, my friends dad come on to me one night and I’ve been extremely uncomfortable since, I’ve never gone back to Africa, although my family have been many times since our last vacation together.

Me and my friend often have really deep and open conversation and I find myself wanting to tell her about the incident but I know that it would break or bound and friendship. I’m afraid that she would make excuses and try justice what he did. I feel that way because the made excuses justifying her bf who was a registered sex offender for recording a girl taking a shower; she ended up breaking up with him but I never liked how she defend that situation.

I’ve been holding this secret for 4+ years now and I’m lit sure if I should tell her or keep pretending it never happened.