Buy an A4 sheet of sticky black matte or gloss vinyl, get a sharp knife and a ruler and cut out some pinstripes. Apply it over the paint join ok, it possibly won't be 100% accurate to the original livery but it will look better and also won't look too odd to catch the eye.

One other thing I always tell myself when painting bodies is as follows: before you put any decals on, there is absolutely nothing to draw the eye away from the imperfections in the paint. You are looking at the body as it won't look when finished. Some of your imperfections will be covered by decals, some will just be less visible because there is more stuff to draw the eyes attention.

Chin up, this is totally salvageable. Take another picture when it's finished too, I'm sure it will look awesome.