Frustrated... any suggestions?

UGGG... hrmph.... I am very frustrated, irritated, and disappointed. I am making a cake tomorrow for a family dinner, luckily I decided to make the buttercream the night before. My buttercream will NOT whip... maybe it is the fact that I am using a mixer that was crappy when it was bought 25 years ago as a wedding present for my mother. Or maybe it's the fact that I added chilled soymilk... or maybe it's that I added soymilk at all. Or maybe my butter broke? I have no idea... either way, I have soup... blah... I spent 42 minutes attempting to whip it... gave up... did some googling... went back, added more powdered sugar whipped for maybe ten minutes.... and gave up again... my soup is now in the fridge.... if ANYONE knows any suggestions PLEASE help me : ( I really wish I knew what to do....