Chevron Accent Wall? Or other ideas…

My wife and I are hoping to turn the wall behind the TV into an accent wall. We both like the chevron accent wall look using 1x3s

The first picture is the wall in question. The second is similar to what we are thinking about doing.

My question is this: if you notice the left hand side has a bar connecting into it. Meaning it doesn’t have a square “edge”

I was thinking we could end the chevron look with a vertical board spaced 1.5ft or so inside the wall to “square” it off.

Does anyone have experience doing geometric designs like this on a “non-square” wall?

Open to other suggestions as well!