my bathroom was this exact shape and had the window too. I got a shower blind. It attaches to the ceiling and rolls down like a window blind. The casing is metal and the roller blind is plastic.
you can get a long arm and a short arm to join together to fit above the length if the bath and the end of the bath.
I had mine roll down to the long side and the short end beside the sink.
If you Google for shower blinds you should find it. I think it was a German company that made them.
worked really well and after it had dried you could roll it up to the ceiling out of the way.