If your partner is interested in sex but you are not, you have a problem that needs to be solved. Why not write possible solutions on a piece of paper and start discussing wether there is a solution to this.
1. You could live a celibate life together.
2. Your husband becomes a better lover so that you will be more interested in having sex with him.
3. You accept that your husband finds his own solution to this.
4. You get a divorce
(continue the list with anything that you can come up with)
See if any of the suggestions is something that you can both agree upon. Continue until you have reached a solution which you both can accept.