oooo... me and Rebif were not friends. Some people do spectacularly on it, I went down hill, fast...
OK, the next section is going to be a little blue, and I may be preaching to the choir, but it may help.
If you have delicate sensitivities, I advise you to stop reading now. And if you or anyone already is in the choir, you can also stop reading at anytime.
A few years back I had a girlfriend who was perfectly healthy. At the time I did not have an MS diagnosis, but I think it caused some minor numbness which made me "last" longer. Anyway, on one long "session" she had "arrived" a few times, and had clearly lost interest and also clearly had had enough. I noticed that her clitoris was no longer erect. I suggested we might bring out her "rabbit" vibrator (it was long distance, I wasn't always around, and I did mention her "health"... oh, and if you don't know what I mean on the device, search google for it), and within seconds, just the thought of it brought her erection back. Now, this device wont help with your husband, I only tell the story because I think maybe some of your reduced interest might be a self feedback loop from your numbness in that region. Now, another time, I brought a small "vibrating egg" to the "party". This small really cheap device allowed us to both "participate" ie hubby can join in, and you may also be "pleased" (I want to be more explicit, on how, but I am sure you will find your own way), and she said it was as if she was constantly "arriving".
I hope this helps, and anyone who might be offended, I hoped you stopped reading earlier. Sorry.