Depression and stupidity

Recently I have been feeling really depressed and I feel like it is interfering with my day to day functioning. I just feel unbelievably stupid most of the time. Today I went out and didn't even shut my front door never mind lock it. I just left it wide open. This isn't the first time this has happened. Yesterday I left the oven on after cooking.
I feel like people put me down all the time and I can't hide my stupidity. I'm so sensitive about it and I can't stand people laughing at me. My confidence is really low.
I exercise, I see friends, I have an active brain as I am doing a phd but in day to do day being switched on, I just can't get it right. I think I know all the things I should be doing but I just can't get it right. My partner and I have had a rocky relationship pretty much since I had my daughter 17 months ago and I feel like he brings me down even more than myself. He gets so frustrated with the stupid things that I do. This makes me resent him.
I have always been below average in terms of being 'switched on' but recently it has started to overwhelm me. I sometimes have panic attacks and I know I am in a bad place right now.

What can i do? I have called the Samaritans before ( a suicide phone line in the uk). I am trying to do all the right things but I just keep on falling down.

Please help

Roseanne