My suggestions. Deal with things in order. Order of what's your responsibility, order of what could ruin your life if you don't manage it right, what you can theoretically control, and order of importance.
First things first. Come clean to your husband. Apologize profusely, tell him how much you love him, make no excuses, dont try to justify yourself, you were in the wrong and you won't do it again and you can't live with lying to him. This almost certainly WILL come back to bite you and it WILL be worse if it happens any other way. For example, what if L breaks down and tells his wife, and she confronts your husband. Don't let that happen. Reclaim your integrity. A crush is no excuse to cheat, and fear of consequences is no excuse to maintain a lie.
Next. Assuming your husband is ok, tell L that you can't see him anymore -- can't be alone together, can't be more than very casual friends in group social situations -- if he won't come clean to his wife. This could either save or end their marriage, but at least they won't be in this dysfunctional place anymore. You're right, you shouldn't force the issue, it needs to be his choice. But you can choose not to be a part of an unhealthy, unfair, unethical situation. What right will you have to complain, if she gets an STD from a partner you didn't know she had and it gets passed on to you and your husband from liaisons that she (and he, if you skip step one) didn't know you were having?? As for feelings, he needs to man up and confront his own hypocrisy. What sort of partnership do they even have at this point, with so many lies floating around in it?
Last. Assuming that L and his wife are ok, then you can decide how you want to tell or not tell the other 200+ people in your town.
Bottom line, you can't have your cake and eat it too, and the fallout could be so much worse, in so many ways, including perception of you in your small town, if you let self-interest continue to guide you over doing what's fair for all involved.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.