Cry it out guilt

I have a 9 month old baby girl who recently mastered pulling herself up to stand but she hasn’t really learned how to sit back down again. Bedtime routine has become an utter NIGHTMARE. Her usual time to go to bed is 6-7PM - these days it will take literal hours for her to miraculously fall asleep eventually. She’ll be showing all the signs of being tired, but as soon as she lays down she will pull herself up into a standing position and won’t stop screaming and crying until you put her down again. No matter how exhausted she is. This repeats forever. Tonight we hit a particular low as I’ve spent 2,5 hours putting her back down again. In the end the screaming really got to me and I could feel myself getting more and more frustrated and getting a bit rough when handling her. Eventually I decided to just let her cry since I simply COULD NOT take it anymore. She screamed for 30 minutes and when her cries got weaker after a long time, I went into her room and found her plopped down in bed, still holding on to the bars of her crib and visibly exhausted from all the crying. I layed her down again and she instantly went to sleep. Now I’m crying on the couch feeling like absolute shit for ignoring her for so long. My partner is currently traveling so it’s been just me for the past couple of weeks and things gets so incredibly overwhelming at times, having to do everything by myself. The guilt is real and I feel like a terrible excuse of a mom :(