What you would be going through is what any married couple would be going through when first embracing polyamory -- the need to keep it a secret. Many folks just cannot be out about it, because it would put them in a precarious position in so many areas of their lives. So, on the one hand, you know it's do-able.
On the other hand, I can understand how you really don't want to be closeted in any way. You have likely worked hard and moved forward with much courage to be out in your community and families as a lesbian, and as a lesbian who is married to your wife. In that sense, my usual response, to say "fuck what other people think," doesn't quite work. I have heard many times how judgmental the lesbian community can be toward women who are bi, even, or who somehow don't live as or represent lesbians the way they "should." However, you need to pursue what will make you happy and satisfied, so some attitude of "fuck everybody else's judgments" does apply. You will be like balancing on a high wire for a while until you find a comfortable place of equilibrium. Your wife may also reach a more comfortable place with it, too. It's also possible her sex drive will return. I am recently post-menopausal and my sex drive has been through the roof.
I feel for you. I think, you may want to investigate whether or not you have any poly groups locally. You can find them through Tristan Taormino's Opening Up » Resources » Local Organizations
or Loving More » Local Groups and Communities
, and also Meetup.com
. Attend some events and befriend some polyfolk. See if you hit it off with anyone who is openly poly and invite them into your social sphere. Maybe if your friends in the gay and Wiccan community get used to seeing you with happy poly people, it won't be so strange if and when you find an OSO. Start talking more to your acquaintances whom you know are poly and pick their brains about how to move forward, since they may know some of the people you are hanging with. You can ask them to be discreet; they're most probably used to that.