As a parent myself
@Moo with adult children. They understand and know that I love them and have done my best to raise them to be independent of me and go forth into their lives and live the hell out of it.
I know they love me too but I don't have to hear them say it every day or have them show it to me every day.
I often told them when they were unsure of what to do that they only get one go at growing up, being young and taking on all the challenges that might come their way. Unless it was something dangerously stupid - once they were older - I held my silence and let the consequences lay where they fell. That is how they learned not to do stupid things. I think that is how we all learn not to do stupid things or to at least stop doing stupid things. Or maybe just wise up to how to live more happily...whatever it was they had to chose.
In other words as I was once their age and did what I wanted to do, now so should they. It is their time to shine...or not.
They know I am ok most days and they know some days I am not. That doesn't mean I need them to be around for either of those days. Until I get too old and physically infirm to manage daily things and there are no other options left, I don't want my children around me unless they actually want to be because they feel like it.
I made loads of mistakes in the parenting area and I can look back in hindsight and shake my head and think what on earth was I thinking or doing?? But it's all too late to worry about that stuff now. My children are off doing their own things and that's the way we all like it.
When we do get together, which isn't all that often, we have a laugh usually about stupid things!
I think you need to grow up! (sorry if that sounds harsh) Get your therapist up to speed on how utterly miserable you are feeling and why and get your friend to stop crying and see if she/he can help you find some alternative accommodation where you clean up your own mess and do your own cooking and start living.
Your life is going to get a lot more complicated if you keep indulging in what your mother/brother etc., are thinking or doing at any given time.
You have wasted enough time on that and it appears to have just made you feel bad about yourself. Believe me, there are plenty of people besides your mother that can take that place if you allow them to do so.
I don't know anyone, not anyone at all....and I have met a load of people - who as parents do not have regrets and as children wish that they could have been parented differently somehow or some other way.
You owe your mother nothing except to go out and live your life the best way you know how and for heavens sake do it now!