Good perspectives from the others.
Ariakas: "There are ways to make it work without having to be 'friends' with his secondary."
When my GF's husband hosts a particular woman at their house she asks me to pick her up before the woman arrives so she doesn't have to greet her. They are not friends. It may not be the optimal way, but Ariakas is right.
As Ygirl implies, this may be an opportunity for your personal growth, too. Do you need to continue to feel low self-esteem? Is this a good time to grow beyond that?
Are you seeing a therapist about that problem, and about your difficulty relating to other women? It might be a good thing for you to work on. From personal experience I know that life is much sweeter when you feel OK about yourself.
It may be that as your marriage grows a bit you can find yourself on a personal journey into a more open, happier self as well. I really wish that will be possible for you.