How to deal with guilt?

I was supposed to take care of Mom and Dad until they passed. I almost had a breakdown from exhaustion in May and my brother and his wife said they would take her "for a few" weeks, which became "a few months" and now hospice said she is entering into the pretransition phase.

I know the past several months (since mid-May) has been horribly difficult for my SIL, who now needs the my brother to be readily available at all times (he works from home most of the time and unless he is on a conference call is available).

One week my brother had to travel to a client (flight home was delayed was cancelled at midnight so he rented a car and drove from Detroit to Memphis).

My husband has heart problems, (had a heart attack 2 years ago) and a cardiac cath and stents placed in October and September because they couldn't do it all at one time. And he's wearing a monitor for a month because his heart still races to dangerously high levels at times so I'm not comfortable leaving him at home.

I realize how blessed I am she has them to take care of her.

I have been going through various stages of grief (anger that my sister-in-law was taking over and making it seem as if I was/am inadequate to take care of Mom, bargaining that if I quit work maybe I could bring her home for her last days (a financial impossibility) to trying to accept by rearranging her room so it doesn't look like her room, and trying to clear out my craft room to make it bedroom that would accommodate a hospital and twin bed so I can sleep in there with her.

I have been flying out to see her once a month ($39 for a ticket) and my brother has been bringing me home since he has our parents' old place and it needed the grass mowed to keep it from looking vacant, but when I went earlier this month and they brought me back, Mom had to come too, and the 6-hour drive each way was made in one day after going to church, which I know wasn't good for Mom although my brother and SIL say it doesn't make a difference to Mom whether she's in a car or at home.

And I can't "just fly out and see her" now because my husband has heart trouble. I had hoped to go out 12/16 and fly home on the 19th, but if I wait too long to make the reservation it will be too expensive to buy the tickets. Rates more than double if one makes the reservation less than 2 weeks in advance, and triple if reservation is made less than a week in advance.

Before my brother's call today, I had been working on accepting that things weren't going to be like they were if/when Mom came home, so I have been decluttering and moving things around so I could turn my current craft room a bedroom so I could sleep in a twin bed by her hospital bed (like my SIL does now), but now it seems pretty likely that even if I were to hurry and retire as soon as I can, it won't be soon enough.

I guess I'm venting more than anything, because I don't think there is an answer to how I feel, which is overwhelming sadness and like I'm totally useless and have failed my Dad and Mom who always said they wanted to live with me until they died (Daddy was here when he passed and Mom was here from July before he died, and he passed in October of 2018) and Mom was here until May.) I talked to her on the phone Thanksgiving day, less than a week after I left there, and she though she didn't call me by name, she missed me, said it was a long time since she saw me and she and wanted to know when I was coming again.

Is there a way to live with guilt and grief without totally falling apart? I know it will be worse when she passes if she's not here and I'm not able to be there for her last few days, whether she "knows" I'm there or not.

Prayers for strength would be appreciated greatly. I know God is in control and is doing what is best for all of us, but it's still hard.

Thanks for listening,