Sorry you're feeling lonely. I understand, because I've been in your shoes of dealing with your partner's new partner, and dealing with all that NRE. In my case, it's even more frustrating because my W is doing all this stuff with her guy, and totally refusing to be intimate with me. I'm hoping our upcoming counselling can get that intimacy back, because I'm definitely feeling neglected.
I think if you keep yourself busy, and try to remember that your husband is now getting to have the fun that you used to have, and remind yourself that this lifestyle takes a lot of communication, it will help you a lot.
When you are with your husband, does he still treat you with a lot of respect and is he still as intimate with you as you would like?