Do I have a future with my sister's ex?

I am a 30 yr. old female in love with my sister’s ex- boyfriend (who is now my boyfriend of 6 mos.). They are both ten yrs. older, dated for seven yrs w/ year breaks in their twenties, and so I have known him since I was fourteen. We have never lived in the same city but throughout my teens he was around and we had a great relationship, a little sister, big brother type. At age 25, he and I started talking over the phone as friends but we developed feelings. We did not act on them and continued our lives in different states, having other significant others, etc. but we stayed in touch very loosely for five years.
My sister and I are similar in our intelligence and sense of humor yet have dramatic differences in the way we live our life. She is very unconventional whereas I have tended to mellow with age. She has emotional health issues and ADHD and a dependence on prescription meds that have not helped much. My boyfriend and her had a tumultuous relationship due to this. They were different people then and have split ways. He has had long term relationships as has she since then.
My sister and I have not talked in two years as she thinks I am responsible for her cat that was staying with me running away. That situation evoked a violent strike of irrational behavior and I chose to take myself out of it for my own emotional health. I love her of course but… you know. I do not know if she knows about us but the rest of my family does, though she only talks to my mother and that is very rarely.
The rest of my family is against us but oddly not because of his relationship w/ my sister. They see me as the baby still and have always thought I just take whatever comes along. I have made it clear that this is my choice and am very happy.
And I am! We have a wonderful life together. We have found friendship, passion, support, challenge, intelligence, and fun in eachother and want to get married when the time is right. My question is: Will it ever? I have already resigned myself to the idea that the bride’s side of the aisle will be empty and never wanted to rock this boat but I have found the genuine thing. Trust me- it is still strange sometimes and it was incredibly rough when I first started falling for him but we are extremely committed now.

When it comes to my relationship w/ my bf, I do have guilt and uneasiness but it is nothing compared to the love I have in my life with him. Unfortunatley, this has caused my father, brother, and mother to hate me. My brother was his best friend, now won’t talk to either of us and my divorced parents (both cold tempered people) have chosen the out of sight, out of mind route as usual. Have I ruined an already ruined family and my chances at happiness with both him and my family in the picture?