Would these colors go together?

Without seeing your room it's hard to say, but you should use painters tape or masking tape to make sure the line between the two colours is nice and straight, then you can hang curtains over the spot (with one colour on each side of the curtain), or else put a piece of furniture against the wall lined up with the line, so that it separates that as a different part of the room. You could also use that half of the wall as a sort of headboard for your bed, or a backdrop for a desk or vanity. Or you can just repaint that last wall so the one wall is a different colour--that will probably look better if you're up to the work. As for which colour to pick, it depends on what you want the room to be like. If you want a funky, exciting room, then you can do the green, but if you want a peaceful, quiet room, stick with the tan.

the green would be a better bet.but....its going to hard to pull that off/ unless your room is very funky.if so. just make a wavy line at some point and make one half green and the other violet.

are you sure you dont have WHITE somewhere in the house? mix what you have left of the violet paint with the white and repaint the last wall to be a lighter violet.

I would use the Arizona Heat. The Peaceful Thyme would be way too harsh.

I'm not sure about how to make the switch look deliberate, all I can think of is to put something special there, or put a curtain across part of your room.

Have you seen on lifestyle shows...get a sponge, dab in both colours then dap on in a chequered style. When dry go over again..it will blend in like a sunset...gradually..so wont look a mess..use a bit of white?