If it was just your acl you would be kinda ok. You have a mcl strain or some damage which is causing the lateral instability. You absolutely can damage ypur knee further. Dont do something stupid and tear your mcl, pcl, lcl, fcl along with the acl. Your seasin is done. Get the surgery now so you can rehab and be strong for next season. I see these injuries every day and would tell anyone the exact same thing.
I agree with Argo, get the surgery now. I had my ACL surgery October 2011 and was cleared to board in March 2012 by my doctor. I busted my butt in PT and honestly feel like if I had not had the surgery and tried to board I would have not felt comfortable at all. I now play basketball several times a week and snowboard as well and my knee feels just like it did before I tore it up. If you participate in any sports that require quick lateral movements you will cause more damage to your knee as your knee will not be as stable since the ACL is torn. Also those braces you get at your local sporting goods stores are basically a placebo affect. A good brace like a Don Joy Brace that most people get after their surgery and the ones you see NFL and College lineman wear, doesnt statistically prevent injuries according the doctor's studies.