You ARE strong enough to be the leader in your own life. Alpha Male is an overused term . . . . in animals that actually have Alpha Males, there's only one in each social group, and he has to die or be defeated by a challenger before there can be a new one. The old wolf dies, and ONE of the young males becomes the alpha. The rest of the pack aren't worthless or pathetic because they aren't that one leader everyone looks to . . . but the rest of the pack generally know their place in the order.
Humans lose that sometimes. You don't have to be the one leader everyone looks up to, the big man on campus. You just have to find where you fit into things. You have to make yourself happy, and truthfully, your wife might or might not go along with that. You can't know for sure.
I haven't had the background you had. I won't kid you; that's a very hard start you had there. But I did come here having spent ten years in a sex-starved relationship with my wife. I hated it. I was furious at her constantly, and I was sure I was a pathetic loser. I was sure she was punishing me for a hundred different things, and what I hated most was when she would tell me that it wasn't me, she just wasn't interested--anything intended to spare my feelings only made it 100 times worse. I was sure she knew how I felt and just didn't care (and who cares how a pathetic loser feels anyway, when no one respects him?)
The truth was she didn't respect me.
I listened to people here (well, usually) and I did my best. I'm still working on it, but our life is very different now. It's not just the sex; I feel like I can earn her respect, now. I respect myself, and the truth is, I didn't before.
You might want to start by thinking about what would make you happy. If you were happy in your marriage, what would that look like? What would be happening? What would be said? Then you can worry about how to get there, but for now, think about your goals.
Have you read The Sex-Starved Marriage? I detest self-help books, but it makes a HUGE difference to read it. You'll see yourself in it, and you'll see her in it. It will help you realize that she might be just as trapped as you are. Just because she's the one who says "no" doesn't mean that she feels like she has any control over anything, either. Please read it.