help!!

Seriously. Can you anyone help me get my daughter to bed? She used to go to bed so easy. 7 pm. Now she just refuses. Screams. Cries. Etc. It is extremely frustrating. Especially since G is working nights. She is currently in her crib screaming. She has been down here yawning and saying nigh nigh. So I took her up. How long do I leave her there? It has been 5 minutes and I already want to scream my head off. A lady I work with tells me E has got me wrapped around her finger cuz I usually go in there right away (or within a few minutes). She says I should be strong and stay out so she knows who's boss and she will eventually fall asleep. This is SO hard to do! Help!