Huge secret.....

Hi ladies. So I'm just going to vent really quick or I guess it's more of getting a huge secret off of my chest. And I'm going to stay anonymous, as I am not comfortable with my past yet to expose who I am. My closest friends and family don't even know this. I haven't even told my fiancé because I know he might do something crazy....

Anywho, when I was younger, id say around 9-12, my father started this routine of depantsing myself and my little sister (she was 2yrs younger than me). At the time my sister and I thought it was a game and would also depants our Father and run away giggling. But as time went on, it started becoming more than just a harmless little game and it turned to our Father stealing our clothes and locking us out of our rooms, so we were forced to stand in the living room completely naked so he could look at us. Then it turned to him showing himself to us and touching himself. There was one instance that I remember that he actually got off and then tried playing it off as it was a joke and was just lotion. I knew better than that though. Now fast forward to me being about 14. I was home with just my dad, my mom was at work, and my sister was at a friend's house. I was on the family computer, which was in my parents room, and my dad got in the shower in the connected bathroom. Well when he came out, he sat down on the end of the bed right behind me and started touching himself, then told me to touch him. I refused and refused. Until he forced me to touch him.... Everything died down after that, but I always could tell he was still "looking" at my sister and I as we were maturing. I am now always super self conscious, and always think everyone is looking at me in the same way that he was. Another thing, when all this was going on, I didn't know what sex was, I didn't know what molestation or anything like that was either. But given he never actually touched us, I brushed it off and tried to forget it ever happened. But now that I'm older (about to be 25), and have 2 kids of my own, I'm now scared of something like this happening to my own kids and I not ever know about it. (My mom never knew what happened when she was at work....And our Father made us swear that it was our secret only..Etc).

I no longer talk to my father, because of other reasons, but I still can't shake my past. I think I've kept it inside for way too long... The only other person who knew what happened was my little sister, but she passed away almost 8yrs ago when she was 15 from a fatal asthma attack.... Idk how I'm ever going to be able to tell my fiancé this information... And again, I'm scared of how he will react.... But I hate that I'm keeping such a huge secret from Him.... I also have an older sister who doesn't know. She grew up with her mother, (we have the same dad different mom's) so we only became close in recent years... She hates our Father just as much, but again idk how she would react if I told her this info....

What would you do? How would you tell your SO? What should I do in general about this whole thing????? :(