sorry it played out like this for u
but i see it in a different view point then u do
if the guy did not want to reach out and find out what is going on with his own blood he has no redeeming values as father and u got off lucky never knowing or dealing with a man like that .......i seen a father infect own son with hep c so he would not have a better life then him (the father)......one son turned out just like him (son had a kid and she is smart full pay for college just on her grades at 16 the son refused to sign the papers because he did not want his kid to be smarter then him ...at 18 she left home and is a porn star now.....i been a good friend have not asked her porn name ).......the other son is my oldest friend in the world he was the one infected with hep c because he refused to be like his father so he attacked him and infected him .......he left did not talk to the man for 7 years then tried it again 2 years ago and father just ripped him off and stole cash from him ......since then the son has moved 3 times and refuses to deal with his father or his brother (if i was allowed i hurt them both for being scum of planet )

i am sorry for the hurt u feel at this point ..........but it could of been worst
the only reason now to even make contact would be to get medical family history from his side ..........for your sister incase she wants kids ....or one of u guys show up with a rare something