One of my boys was like this. He cried so hard on the first day of preschool, he got a bloody nose! He cried for months. He has difficulties with transitions and we've had to be aware of it and work on it for years.
Sounds like the pretend play is great, her self-talk "mommy will be back" is fantastic. Now, you've just got to let her work through it. It may take a while. My son stopped for a while and then started up again. And whenever there was a change in his routine, he would cry. The teachers were aware and just dealt with it.
I think some encouraging words, "You can do it." "Take deep breaths and I'll be back before you know it." would be helpful. I think lots of hugs regardless. But I do agree with leaving after a big hug. My dd sometimes asks for another one, and I do it. We have a secret ritual of blowing kisses, too, which I think makes her feel better.
You might consider reading some books on separation. "The Kissing Hand" is a great one.
Also, don't worry about other moms. Who cares what they think? Their opinions just don't matter in this situation.
