Precisely WHY I continually advise against the use of a cover on an AG pool - I see it every winter.
Wherever you get cold weather, it is very unlikely that owners will be able to stay on top removing the water that collects on the cover, mainly because it turns to ice first. The best winterizing is to not use a cover, keep the return and skimmer open so they stay drained to their bottoms and can't freeze up. if you must use a cover due to leaves, pump and clean it off after the leaves are done falling, remove it and let the pool be for the winter.

At this point, your best way to attempt saving your pool is to completely release the cover, once things melt, make sure your return and skimmer are able to drain and the cover does not block them, you'll have a big mess to clean up, but it's better than a broken pool.
The crease on the wall may come out in sprintime and all might be well.

Do NOT cut the liner, a small wrinkle in teh wall is likely minor.