No need for guilt or shame. You have known him longer and are more related to him than anyone ever will be. Only guilt you should feel is not giving me your sex. But, we can fix that.
If they don't have children, then you atleast have a slight chance to have him. My experience is almost like yours but we had a one drunken kiss and slight touching when we were in our twenties. Then, ten years I waited, thinking all kinds of ways how I could tell him how I feel. Nothing happened until for the sake of my sanity I really needed to talk about it and to tell him how I felt about it and him. I was running out of time because I had waited only him and the right time to tell him.
He already had a girlfriend, and like yours, she is really sweet. I was so afraid but also desperate when I finally told him. We started to have sex though. For ten years I had waited him and then another five years I was hoping something would happen and they would break up.
When he told me they are pregnant, I knew I had lost him forever. It is easy to say, but then i felt so bad and hurt that I even told him that if he liked to have children so much, he should had got me pregnant. I would have gave anything if we could turn back time. I felt so hurt then, but what could I do? Then I thought I would break up with him, but we continued having sex until his children needed more of his time.
Their children are wonderful and she is my friend, but still there is one man I would like to have, or atleast share with her, but I just can't.
Keep going and no guilt. We all need our outlets and things just for ourselves. I've been having sex with my hot older sister for years, including before and during her first wedding. Love the fact that I had her right before and right after her asshole ex-husband and he never knew it. We've spent overnights and weekends together, and it just goes well. The sex is great, we know what the other likes, and it's always been our thing, no matter what our other relationship situation was.
Many times, at my own house and hers, if we were in need of each other, we'd sneak away from the gathering going on, away from our sig. others, and have at it. Funny, we've always shared a thing/fetish for her long, always done nails, and, if they were done my favorite color, jet-red, at a gathering, I knew..It was on. That was one of our hidden, but known, things...D's nails done jet-red (or, as she called it..her fuck-me red), we were absolutely having sex, and a lot of it.
