Sorry this reply is lateish, but I've only just seen your question.
I'd be inclined to leave any thoughts of playgroup for at least 6 months, then consider giving it another try, maybe just after the summer holidays.
Before she starts, speak to the playgroup staff about a phased entry, where the first day you leave her for 5 minutes, then next time 10 minutes and so on. One of your daughter's big fears will be that you're not going to come back, so doing it this way might just reassure her. Try to keep to the 'schedule' even if she cries the whole time, but obviously within reason!
I've seen children do this before, and after a break from the playgroup, they've gone in absolutely fine. Remeber she's only very young, you've plenty of time yet.
Keep us posted. x
P.S. Almost forgot, in answer to your main question, keep on with the toddler groups etc just as normal, and gradually she will build up her 'trust' (for want of a better word) in you again. It'll take a while (been there, I know!) but it will come.