Sisters kind of ex?

This year has been really hard for me, in September I was sexually assaulted and it took a while to even come to terms with the fact that it happened and am starting to actually deal with it now. One person that was a great help to me during my initial acceptance was this guy that I had been chatting with. About 2 years back he and my older sister hooked up a few times but nothing happened because after they jumped into bed together she wanted a relationship immediately and he felt they should wait a little longer and really get to know each other. I feel bad that she didn't get what she wanted but now she is with a guy who she really loves and they live together and stuff and I want to be happy too. I feel bad if I seem really selfish it wasn't meant to hurt her but now we are seriously talking and dating could be close and we haven't told anyone cause he is a close family friend and my parents know that my sister and him used to talk so I'm not sure how to bring it up to my sister, or my parents for that matter. ** Sidenote: When we started talking he messaged my sister saying he was sorry that them dating didn't workout but he was so happy that she met someone and was doing well and that he hoped they could remain friends, she seemed satisfied and thankful he did that** So any ideas on how to maneuver this? Please don't start lecturing me about only having my sister forever and stuff and that I'm a jerk or whatnot. Thanks guys!

My advice would be to just tell your sister that you two are interested in each other and everything else will follow (assuming he is as nice as you say he is).