Surprised by depression
I retired last month after many years with the same agency; the job became too stressful and there were no opportunities for advancement, so I retired.
I was so elated that first week but by the middle of the next week I became bored and then a couple of weeks later down right depressed.
I don't miss the job at all and especially don't miss the dread I felt all day Sunday. What I do miss is the structure of my day, which was very busy; I usually was gone from home for 13 hours. It's like going from 120 mph to zero.
I am looking for another job but can't decide if I should take something that wouldn't use up so much time or get back into my former schedule if something less stressful turns up.
You are experiencing what many of us do... and it does get better in time. Be patient with yourself.
As for part time or full time working, only time will tell. When the job is offered, you either accept and try it out, or decline. It's your time and your retirement now... you are no longer forced to do five days a week, UNLESS you enjoy it.
The good thing (to me) is that you are considering work again... that means your brain is still functioning, and you aren't totally depressed. You are considering your options... you'll be just fine!