What do you mean by other side?
Only one side is in front of the player right?
If you are mirroring the player, The players angle stays the same, only the animation is mirrored, so you would have to create a different event for that..
From the top of my head, when mirrored to get the same effect, the angle(player.x,player.y,mouse.x,mouse.y) should be between player.angle+135 and player.angle+225
I told my dentist I had trouble with my teeth and asked her to fix it without looking in my mouth..