Alright cracks neck
The biggest aspects is that you are feeling guilty over things that are ether not in your control, things that are the fault of others and simply for being human.
Much of your guilt is simply taking the burden for things you could do nothing about. You could not stop your body swapping with her, you did not choose to leave your family behind for this. Those things in particular are completely out of your control and sucking the life you could be using for simply what came to pass. Accept that they have come and move forward.
Armsmaster? He is a man who had a routine and one who has issues connecting to people. This is likely a shock to him that he doesn't know of, so many things stressing him out and you sadly are another. BUT
That is not your FAULT
If he does not wish to have a close relationship then it is not worth it. Do not think your own time is lesser then his own simply because he is Brianne's biological father. He is simply a man, not a icon of virtue. Stop taking guilt for another person's actions, they are not yours to bear.
The 1010? You have given them life. Yes they did not ask and nether did you, but both your lifes have already been enritched by each other. To feel guilty for something like this...don't wallow and strive to do as best as you can and the best they can be.
The last part about Cauldron and not using your powers to the fullest? Pika your expecting yourself to be less then you are. Your not perfect nor should you expect it, even the smartest and strongest are not perfect. Don't force yourself to feel guilt, use it as a drive to say "I feel I can do better, I will do better"