I’m not a great mum, nor am I a good person
I am really sorry that you are feeling so down in the dumps today. I just want to single this comment out as I do not believe it is true!
You sound like a lovely person who is currently struggling a good deal. PTSD is hard, having other mental illnesses on top of that is even harder. You are trying your very best && it is unreasonable to expect you to do better than your best. Is there anything you can do to comfort yourself?
A nice blanket, coffee, a silly movie? (I love Shrek, lol.) When I get really dejected like this it often helps to bolster myself by focusing on some self-care activities like making a coffee && playing Stardew Valley. I try to tell myself that these feelings of suicidality are transient && I will not feel like this forever.