And breathe.
I'm with you, along with about every other parent of a 2.5 year old. They are hard work . Period.
I describe my dd as Jekyll and Hyde - she can be truly awesome and have DP and I in stitches with her little ways, then she switches and can test me to the brink. Last Friday I walked away and left my daughter with a relative she hardly knows, as if I'd stopped close to her to appease the situation I would have lost it. I was also in tears as I walked away
My best advice, although this is blind leading the blind here, is to reflect on the situation at the soft play, and think what you could have done differently? Why didn't she want to leave? Was there an urgency to leave? Could you have approached it in a different way?
It's already happened now and you can both talk about it afterwards too. Ask her why she got upset about leaving, explain to her your expectations in the future (no tears when mummy says it's time to go) and most of all, say you love her and don't like her being upset, and they you don't like to be upset.
I suppose I want it say it is normal to get upset and normal to get angry too. It is also normal for your toddler to behave this way - she thinks the world revolves around her, and it does in a way.