Okay I haven't read the whole thread yet--but I think those feelings are completely rational! It's just that it sounds like they are getting overwhelming, too intense.
I can relate. My DH is 19 years older than me, I'm 27. He and his ex are good friends. Well, I'm friends with his ex and we spend time with the kids and her bf and everybody. They separated around ten years before we got together, thirteen years now, so there's nothing lingering. He didn't really want to split up, it was her idea. And they have a son who is about to turn 17. We aren't TTC... I would like to be, but neither of us are ready. I plan to start as soon as we are though, because of the age factor. I'm afraid we'll never be ready and I'm not too confident in either of our fertility. *sigh*
I used to feel envious of their past together. She knew him when he was young. He's good looking now, in my opinion, but he was even more good looking back then. She knew what he was like when he was just starting out in the world. It used to bother me that our first home won't be his first home. Our first kid won't be his first kid. She knew him when he was at his most passionate in some of his interests that he's now cynical about. And I also wish for my own sake I had met him when I was younger. It would have spared me from some lame partners, and at the time I was even more involved in some interests we have in common. I might feel envious in some way over his son, I find his son to be a sort of baffling silent teenager (but a really good kid and great person as well), but so does everyone more or less so I remind myself of that when I feel awkward about it.
Those feelings just faded. I think it's natural. It's one of the downsides of falling for someone with a considerable age difference between you. There are upsides, too... he's more experienced with life, and his personality isn't as unpredictable as it can be with some young guys. Is it worth it? Who knows... this is the hand I've been dealt. Love is never entirely without flaws and challenges, otherwise we wouldn't learn much from life.
I say this with all kindness... I kind of suspect there's a certain craziness that comes with too much TTCing
That may be what is augmenting your perfectly reasonable feelings.