Heartbroken

I go back to work tomorrow night (work nightshift at the hospital). My husband also works nights. My mother (who is retired) is planning on spending the night at our house to watch our LO (16 weeks old) while we work. She has been over to visit multiple times per week the last few weeks, has done most of her night time routine several times already, and LO didn’t seem to have an issue with her-shes even taken naps on grandma multiple times. The only part of the night-time routine she hasn’t done is that after her bath and feeding LO gets rocked to near-drowsiness before being laid down in the crib-i’ve always done that part. Tonight my mom wanted to do the whole thing without my help as a trial run for tomorrow, and everything went great until she tried to rock her at the end of her routine to put her down. LO screamed-like full on crying which she hardly ever does-for 40 straight minutes while my mom tried rocking, patting, singing, walking, burping, shushing, pacifier, everything. Finally called me back in after 40 minutes and handed her to me and LO immediately stopped crying. It was heartbreaking listening to it and knowing she was crying FOR ME (I was literally in the other room crying too 😭). I had previously had no worries about going back to work but now I want to cry just thinking about her doing that tomorrow for who-knows-how-long since I won’t be here for her. I completely trust my mom, and she is really good at handling her crying and loves her to pieces, but as a first-time mom its so hard to think about. Unfortunately, quitting my job isn’t an option-i’m the main bread-winner. I guess just looking for any suggestions people might have to make this an easier transition on my baby?