Lucky you - you're married?
I wouldn't call that alone. I've never been in a romantic relationship and I'm almost 41. I envy you.
It's all about perspective here. You may not have the friends you want, but at least you found someone willing to commit their life to you.
Also, as long as you're still alive, you have the power to change and grow and adapt. This includes learning how to make the friendships you want to have. You're not a rock and immutable. You will change (that is a guarantee of everything in the universe), and you have the power to mold that change through the choices you make.
It's a heroes journey, and you are the hero.
Loving Kindness Meditation will dramatically improve your spirits; give it a try for just 3 days: http://www.youtube.com/watch?v=sz7cpV7ERsM