How to tell older guy i like him

I am afraid to just come out and tell him because I do not want to get rejected. He is way older than me but i am attracted to older men. (20+ age difference) I had a random dream about him and now I really want to see if there is anything there... We have talked maybe twice before, and he has been over to my house.. he is my little sisters, bestfriends dad. if that makes since. I dont want to try to start talking to him and then make things awkward if he isnt interested... He has asked twice over FB for me to hang out with the family (because my little sister is friends with his daughter) but i was afraid to go. this is silly but i have tried "poking" him on FB lol he poked back and i poked again but he hasnt responded, he prob thinks i am weird...

As long as you are over 18. Then next time he asks you to join them you should. See if there is a vibe. This way you can determine if he is asking because he likes you or just because you are the big sister. Just tread lightly because you are right about not making things awkward for your sister. If you get a vibe then be straight forward. If he is into you then take it slowly from there. If not then handle it maturely and move on.