Researching, darling. You're sacrificing yourself for his happiness. Let me tell you what happens when I (habitually) do this for my husband. He gets MAD. He feels like I'm pushing him away, that I don't want him, and that I can't be trusted to make my own decisions because I'm like a lemming--I *must* throw myself on a sword, any sword, to make him happy.
I don't know why no one has come out and warned you about this, but typically things go badly when someone turns to poly to fix their marriage. It's not a cure. It makes things harder. However, the most wonderful thing about poly is the communication skills you learn, which actually do help marriages in trouble.
I'm trying very hard to remember all the things I learned when I was trying desperately to fix my sex life. In my case, it was the opposite--I have a HIGH libido, and Easy doesn't--but most of the material out there deals with your situation and not mine. It's really not unusual to lose your sex drive, as you've seen from all of the other posters. It is certainly because of many factors. Another one I would put forward is, how is your connection to your husband? Do you feel alienated from him, isolated, resentful? You can love someone and still resent things about them. Work on your connection. One thing I remember being put forward to help a flagging sex drive is to put time aside just for touching, with NO SEX at the end--agree on that beforehand. Just enjoy each other's bodies and company. Oh yeah, and try to do some talking, just about things you enjoy. Sex isn't just about sex--well maybe in some relationships, but you get my point, right? You need to connect to your partner and understand that he's connected to you.
I recommend reading The Five Love Languages and figuring out what makes you feel loved, because it sounds like you desperately need to get some loving reinforcement. Your library should have it, and it can be a quick read. Just skim it if you have time for nothing else. Also, I did a LOT of reading. I would suggest reading at least one book on polyamory--for example, if you find The Ethical Slut horrifying and upsetting, poly is probably not going to work for you. Reading books on polyamory will also help you learn more communication skills. I believe that I found the self-help books I read by googling "low sex drive book" or something like that. Just toss out the words that are in your head about what the problem is, then go to Amazon and read the reviews to find what's interesting. Never forget that the library is a free resource and will let you check out all of the books that you want.