I'm guessing you won't be the first person to blow off treatment in anger, Katie.
Ring them, email them, go and see them - explain your situation and apologise.
Sure it's hard - I'm not great at humble pie myself - but to blow off your group leaves you with what exactly?
Whether this is an ending or a beginning depends on what you do next really.
oh- and it's always best to consult a dr before beginning, ending, or otherwise changing meds (medical disclaimer LOL)
D