Hi Vanessa,
Welcome to SR, but I'm sorry for what has brought you here. Has your husband taken any steps toward his sobriety? I would watch his actions, not his words, to see how serious he is about working a recovery program.
As far as trying to find a balance between being supportive and setting up boundaries, that is something that can be very difficult to do with an addict. By the time we find out the truth, chances are they have been actively using for some time, which means they've had plenty of practice in lying and covering things up. Someone who is currently using will lie (you already know this firsthand), manipulate and turn things around to protect their addiction. It can get to the point where you feel like you're going crazy because you start to question your own judgment and your own sanity.
I understand that you want to save your marriage. This is the man you love and the one you chose to spend the rest of your life with. I hope your husband is able to get the help he needs, but he needs to take an active role in his own recovery and commit to it. Like I said, watch his actions, not his words.
Whatever you decide to do, I hope you will continue to come back and post. There are many people here who have been in your situation and know what you're going through. You'll receive a lot of support and advice here. Like they say at the meetings, take what you need and leave the rest. Good luck to you and take care of yourself.
Hugs