Karen,
I know how you feel, at least a little bit. We were there. When we were celebrating our 25th wedding anniversary I wasn't even sure I wanted to be married still! My husband had a nice new diamond ring made for me and I didn't even know if I wanted to wear it or if I'd be tossing it out before long.
We were empty-nesters at that time too; active at church; ran a business together; had lots of friends. Everyone thought everything was ok. Finally I confided in a good friend that it wasn't all great. She encouraged me to talk to my husband, tell him truthfully how empty our marriage felt to me, and ask him if our marriage was worth some counseling sessions. She referred me to a good male Christian counselor. My husband agreed to see him.
The turn-around wasn't instant. It took time and a lot of hard work, a lot of honest soul-searching for both of us, a lot of repentance and seeking the Lord. But it was worth it. We are now on our way to 41 years. At our 40th anniversary we had a big party and renewed our vows. We are happier than we've ever been together. We are much more realistic in our expectations of each other, we are quicker to forgive and to ask for forgiveness. We are softer and kinder to each other. We are more in love. People see the difference. We want to be together forever and love spending time alone together doing simple things, just having fun. I Cor. 13 has become my guide in loving my husband.
I want to encourage you to speak with the Lord about how you're feeling. Then see if He would have you go to your husband and tell him gently how you feel. Consider asking him if your marriage is worth a few counseling sessions and a little time and energy. Above all, be gentle and respectful, pray and ask the Lord what to do and how to do it. I pray that your testimony in a few years will be greater than ours and that you will live the rest of your days serving the Lord together from a place of deep love and unity.