Levon, my words you have been through a lot. No wonder you feel the way you do. But do not dispair, you have a new job and a new place for you and your son.
These feelings that you are going through are normal. Especially after what you have been through. Please don't be hard on yourself, you are grieving the loss of your mother. And of course you wanted to be at her side, but you can't help that you weren't able to. So let that pass. You sound like you were close to her. She would want you to go on with life as you are doing.
I hope that this helped you a little. It is a hard time of year right now, everybody has been feeling a little down. But with help from us, you will feel better soon. You have come to a good place. We are here for you.