Could you just trim the other side by 1" and make them all 7 1/2" squares, then make up the difference with the border or sashing?

I was going to suggest the same as crafty14. This is what i would do if you have enough fabric. So sorry for you but we all have been there.

Don't throw away. Make pot holders and donate to a soup kitchen. They don't care what the pattern is.

Did that once to a whole quilt. It was the alternating squares so I was creative and inserted a strip going sort of up and a strip going sort of crosswise and then recut the block. Did not even try and make them straight. I also piece a lot of "miscuts" or just to use up the leftover fabric. In the overall look it works. Most often people don't even notice the extra seams.

So unless it is a show quilt, go ahead and piece the fabric and recut.

Cut a 2"strip of the original strips and sew it to the edge, lining up strip so it matches, then press and trim to size.

I think I'd try different arrangements of the blocks you have already cut. You might get something wonderful from them. Just call it a design decision!

Oh man I'm so sorry this happened to you. If this is the first time you've done this your doing well! I seem to make a blunder more often than not. So I've have got into the habit of double checking. My only suggestion is you cut a jelly strip in half add to your squares and then size them up. Or change the pattern! Good luck in whatever you choose. Hope we get to see what your creating.