If you think you're able to tell your family, then I definitely think you should. They can't help/support you if they don't know. As others have said above, they may react with denial, and if that happens then you need to seek support from someone else you trust. I hope they don't deny it, though! I hope they believe and support you right from the start.
Since I don't know you / your situation, I can't really predict what will happen if/when you go to the police, but I can tell you my own experience.I was raped several times by my father (along with a long list of other forms of abuse). The actual rapes took place from ages 13-15, after which point he simply dropped off the map. I told my family when I was 18, and went to the police when I was 19 (months later, not a whole year).
I was asked to give a statement initially, and my mother was allowed in the room with me. She was interviewed as well. My father's sister was phoned and interviewed, but since his brother lives in another country, that's the only family they contacted. I was assigned an officer who was in charge of my case, and she kept me in the loop on a monthly basis for 2 years. In that time, my father was located and questioned. He denied everything, of course. I was interviewed again, this time alone. He was issued a "no-go" order which would become a formal restraining order if he violated it. Not allowed within X radius of my residence and not allowed to knowingly enter my place of work, but allowed in the vicinity. He had been identified applying for a trades certificate program at a satellite campus of the university I was attending. As far as I know, he was allowed to pursue the certification if he still wanted to. I don't know if he did or not. While the case was open he was not allowed to renew any licenses, and since he's also still owing major amounts of money in taxes and child support dating back to 2003, supposedly that's still in effect. I'm 99% sure I've seen his car on the road in the last year, though.
After 2 years with no new developments, the case was considered cold, and the police stopped contacting me. I was and still am entitled to free support services through the police, should I ever need counselling/etc. and I'm not able to find it on my own. If, at any time, my sister ever decides to contribute her statement, or if someone else places similar charges against him, the case will be re-examined. I don't know if any of this would show up on his record if he were to apply for a job that requires a criminal record check, but he prefers to work under the table anyway.
I'm told this is, unfortunately, common. I mostly expected this going into it. I did it because it brought me a little peace, just knowing that I had done what I could, and I also did it because I'm convinced that he has done this to others, and perhaps my case against him will make things easier for the next brave soul who decides to call him out.
Stay strong!
