Everything is pointless and everything I do is useless

I know that a big part of how I'm feeling is frustration and the other big contributor is my depressed phase which has naturally come around.

For the last few days my enthusiasm has been gradually dropping off. I've barely touched my writing, I've not done any knitting and I can't say I feel like doing anything. I feel like there's no point to my writing, that there's no point to my knitting or toy making. I feel like I'm coping rubbish with Angel and I'm in a bad mood almost constantly despite the fact that I've been trying to snap out of it. This morning was hard for me to persuade myself up and T and I decided that I would do his work today while he looked after Angel and the house, it didn't go to plan though because the computer was going extremely slow so although I got some stuff done for him I was bored and got steadily more frustrated. Now I'm sitting here not feeling very hungry and I'm just feeling generally angry and tired and frustrated and fidgety. I have a bad feeling that this will end in self harm, I was only thinking this morning that its been a while since I've hurt myself, typical. Maybe having a smoke will help, it does seem that if I smoke and its only a few a day if that then I tend to self harm less, although I'm not sure if that's a coincidence yet or not though, I only started again recently.

I think one thing that's brought this around is a near miss that I had with a job as a manager of a nursery. It was going to be in the same county as Ts family lives and we were talking about us moving there. I missed the opportunity because I was too late to accept it.
Then we talked about me extending my business so I'm the main earner and eventually getting a shop, but I just can't manage it alone, it's too much expense and I'm not am army alone. I'm not good enough and I never have been in anything.

Maybe in a few days this will pass but with the nightmares and everything I have a feeling it will be a few days at least.