I am the author of Sweater Surgery and I would like to try to help you with your project. Sorry you are having trouble. You say you tried to sew but it didn't work, I am curious why not? I sew every type of sweater from lacework , standard knit to felted with no problem. I often use the slight bit of unraveling as a design element such as page 54-55 scarf
A. Sew a running stitch before you cut (like when steeking a sweater)
B. Cut the sweater and sew the seam twice once for the seam and once to secure edges.
Please ask any and all questions-sweaters are sew much fun to design with, I want you to have success!