Potty training and rough nights

Hi everyone! I am hoping to find a little help and advice from you all. My 20-month old DD took an interest in potty training about a month ago. She attends daycare and was apparently inspired by the other potty-trained kids in her class. She wears underwear during the day and averages one accident per day. She is so eager to 'go potty' that I have continued to put her in undies, despite her accidents.

Before last week, DD was sleeping through the night. Now, she wakes up consistently at around midnight, every night, saying 'I go poopy'. She usually has a wet diaper, so I change her diaper. She asks to go potty and she usually tinkles one or two times. She wants to keep going on her potty but I've noticed that after the first two tries, she doesn't have anything left. So I put her back in her crib. The problem is.... She won't go back to sleep! I usually pat her bum(part of her nighttime routine), give her her stuffed animal, and wait. She closes her eyes and seems to fall asleep. But as soon as I walk out of her room she pops up and cries. And cries. And cries. I have tried to let her cry it out but my DH cannot stand to hear her cry. He has brought her into our bed almost every night. I know that this cannot be the answer for her or for us.

So, I am wondering... Should I be going in at night when she wakes up crying? Should she be wearing diapers or undies at night? Did anyone stick with 'undies by day, diaper at night'? Should I be getting her up to go potty or just
change her diaper? How can I get her to return to sleep?

Thank you in advance for all of your advice!