Incidentally, my husband isn’t going to let me stand either while he remains sitting.
Fair enough - you have reasons to sit, and he has reasons to stand. And people with babes in arms are not responsible for either of your decisions - to sit or stand.
The way I see is like this:
Suppose I have a baby. I want/need/am desperate to get back to my hotel room, so I squeeze onto a packed bus with my baby in my arms. If I'm doing this, it's because I am confident in my ability to stand holding the child. I'm young, healthy and have great balance, and have had practice toting this kid around for months now. If someone offers me a seat, I'll take it with gratitude. If no one offers me a seat, I won't be resentful.
Suppose I need to sit, due to an invisible disability. I will wait for the next bus, rather than get on a packed one. I will move as far to the back as I can in order to reduce the risk of someone with a more obvious need for a seat standing in front of me. And I will sit, hoping they're not resenting me, but not feeling guilty about it regardless.
Suppose I feel strongly that it's my role in life to give up my see to pregnant women, women with children and/or the elderly/infirm. Then, invisible disability or not, I will do my best to stand. I won't resent them for getting on the bus, because I'll understand that it was my choice. I will bask in their gratitude, and hopefully that'll make up for any pain I might be feeling as a result of my own decisions.
Everyone's just trying to get back to their rooms! No one's in the wrong here.