Gosh, this is getting hard to read.
It reminds me that people mistreat their tiny ones all the time and I can't do a thing about it.
As a 30yo women, I cannot believe that you could not deduce that leaving a tiny baby crying in her crib for an hour and half was not a good thing. It doesn't matter if you check in on her. Really? Oh my word. My heart is actually aching. Let her cry in your arms. Continue to comfort her.
The only time she should go into the crib is if she is sleeping or if you are at an unhealthy wits end and feel you will harm her if you don't get a 5 minute break.
Unfortunately, she is now most likely associating her mother leaving with your neglectful care of her. She is expecting that mama leaves, and I am confused, scared and cry in my crib. So, she cries knowing what is coming for her and not knowing when it will be over.
She has no concept of time. If she eventually stops crying in her crib, it's because she as disconnected herself and lost hope. She knows no one will take her out to comfort her. You have damaged her trust.
She has no ability to connect what you are doing. She cannot "fix" herself. She is not able to join, "I'm crying and so she puts me in my crib until I stop." There is no way for her to mentally do that. She does not have the developmental ability. I'm just so sad for her.
And with what you are saying about the aunt..

I just cannot believe the disrespect people have for children. Just imagine yourself in her same feelings and situations.
The bashing for her mother should stop until we know the facts. For all we know the mother has no idea of how bad it is for her baby.