Just because your wife is going through menopause doesn't mean that the sex has to stop. My wife and I are both 63 and we still have sex 4 to 7 times a week most weeks. She went through menopause just after she turned 40 and we still had sex on a regular basis, except for the occasional times when we were having some relationship problem that resulted in arguments.
I just discussed this with my wife to see what both of us could remember from over 20 years ago. When she went through menopause, she still wanted sex and to be intimate, but it was uncomfortable for her. She saw her GYN and he put her on HRT. She originally used the typical Prempro, but after a few years changed to the plant based estradiol patch. Both of these solved the vaginal dryness problem and made sex great again, but she got 2 benign cysts in her breast on the Prempro. No problems with the patch. When the study of HRT came out that said that it increases the risk of heart disease and breast cancer, she switched to just the Estring estrogen ring that is inserted into the vagina and is replaced every 3 months. This has worked great for about 4 years.
Recently, we have investigated the HRT study and have discovered that it was done with women using a strong level of Prempro, which is estrogen from pregnant mare urine and synthetic progesterone. She is now going to talk to her GYN to get back on HRT using plant based estrogen again and plant based progesterone. He never wanted her to get off of the HRT.
HRT has other advantages too. While on HRT her bone density was stable. Since being off of it, she has been taking Fosamax and has still lost 4% bone mass.
Have your wife discuss the various options with her GYN before you write sex off as a thing of the past. It doesn't have to end. We find it as good as it ever was now and better than it was at times.
If I knew of a libido killer that I thought would work, I would have also given you that information, as it is your final decision as to how you want to live your life. Perhaps someone else knows of something that will work for that purpose. Any investigations that my wife and I have done on things that can change libido are things to raise it, as she would like to be more aggressive with me in the sexual department. I'm sorry that I can not be more helpful to you as to your original question, but many times people help others on this and other boards that I read and write on by giving them information and/or suggestions on options. Most of the time those people take that information into consideration, even if they later discard it.
Another thing to remember is that peoples attitudes change, sometimes weekly and sometimes yearly. My wife and I have been together for 29 years and most of that time has been very good. However, there were times in the middle years that we had problems. We would have arguments and say things that were hurtful. It seems that men can be ready for sex right after an argument, but women will avoid it for days until they feel better. That is the way that we have been. There were times that my wife wouldn't want to have any type of intimacy for days and one instance that I remember for nearly a month. She would either stay in the living room after I went to bed and watch TV until I fell asleep or bring a book to bed to read and tell me that she just wanted to read. Things have been great the past year or 2 and good most of the time, but I think that how the relationship is going has a lot to do with the desire for intimacy, especially for women.
We were more likely to have arguments and problems when we were both stressed at work and tired and that would cause us to be more highly strung, especially me. The more I would try to press her for sex, the more resistant she would get. I finally realized that if I just waited a few days that she would again want some affection and that would normally lead to her wanting sex. Most women seem to need affection more than sex. Women who are looking for a partner sometimes tend to use sex to get affection, but those who have a partner of many years have no desire to do that and then it is the job of the guy to try to give her some affection, without projecting the idea that he expects sex for it. That has worked for me and women on another relationship board that I read have said the same thing.
I certainly don't know the situation between you and your wife, so I have no idea what might work and what doesn't have a chance. However, I have done a lot of things wrong in my relationship with my wife and have learned that women take a lot longer to get over something than most men do. Sex for them has more to do with affection than love, or at least the quest for those, than it does for men. A guy doesn't need to have love or affection to get what he needs from sex, but most women do, especially those in a long term relationship.
You can either think about this or completely ignore it. That is your choice. However, if it were me, I would want to try to find out the root problem of your wife's lack of desire for intimacy than to just kill your own desire for intimacy and sex.
I know that SSRIs, used to treat depression, seem to kill libido in women. I don't know what they do for men, as it is usually women who write on this board asking how to get their sex drive back after being on them. 5-HTP is an over the counter supplement that increases serotonin levels and works in much the same way as SSRIs, which are by prescription. I have read that they decrease libido, but I don't know how much. They work for depression and help sleep.
You are the one who has to decide how you want to solve this problem. The only thing that people on this board can do is to give you suggestions, and those often include options. Most of us take a lot of time to try to help people. Sometimes we succeed with some easy answer, but often the problem is much more complicated and can have multiple possible solutions.