2006 Nissan Altima Broken cabin filter cover

Hi!

I was trying to see if I can change the cabin air filter in my car yesterday, as the Nissan car dealership wanted to charge me $100 to do it for me. Everything was going well, until I tried to get the cabin filter cover off. It was really hard as I could not pull up the supporting tabs as they were tightly secured. And not to mention that I broke a nail trying to open it, so you know I had to find another solution. So I got this bright idea to use my key to flip the tabs up. Well, it worked, but one of the tab pieces, the part that actually makes the cover snap in place, well, that broke off on the right side. So now, only the left side of the cover will snap on, and the right side of the cover is kind of open. My first question is how in the world do you get the cover off without breaking it? My second question is where can I find a cabin filter cover for my 2006 Nissan Altima since I broke mine?

Thanks for your help! :)