I feel so sad reading this thread. What is it about being a mum that means that we think we have to settle for second best?
We always have a choice, and if we can do nothing else we can always change our thinking. Everything we believe is a subjective judgement. So if we tell ourselves, 'my life is crap', that is the story we believe.
So that also means that we can stop the recordings in our heads and change them. If you want to tell yourself that your life is great, then you can. If you want to make your reality a world where things only get better for you, you can. For example, if you do a job that you don't like, you do have a choice about quitting it, even if that would mean that you lose your home. The choice you make is to keep your home, provide for your kids etc, so you keep doing the job. Just switching your thinking to 'I have a choice' is a step towards having a better life.
With regards to relationships, the only person whose love and approval that you need is your own. Framing your world so that you need the love and approval of others only ever leads to sadness, because maybe they won't love and approve of you, at least not in the way that you want. And when you don't require things of others then you are free to love them unconditionally.
I understand about the feeling of 'wasting' talent, I made what I thought for a long time were 'bad choices' as a teen. But they played a huge part in making me what I am now. I can look at them clear-eyed and see that they have made me more aware. And at 39 I'm embarking on the career of my dreams - it's only too late if you don't start now.
As for not knowing what to do, a good rule of thumb is to work out what you love, and do more of it. Works out just as well for jobs, recreation, what to cook for dinner...
We are all responsible for our own happiness. Life throws at us things that make that very, very challenging - I know that. I've had times when I hated life, hated my family, hated myself. But I give nothing and nobody the power to take away my right to decide for myself whether to find happiness/peace/contentment. It begins and ends with me. And if I can't change what is going on around me, I can at least change what I think about it.