You could be me....I really started biking with my second husband, who I loved terribly, terribly. I never really loved my first husband, we were married young (I was 20) and stupid...we were good friends but not much more. I thought my second husband was THE ONE....but he never felt the same about me. I don't know if he actually carried through with his feelings for the other woman, but he had them, and that was enough.
I thought biking, since it was something we did together, would be too painful for me to keep up. But it hasn't. I bike more now than I did.
Keep pedaling. It will get better.