LE - As others have said and I've said plenty of times. Only you know when your done. I remember MFT repeatedly asking me if I was really done when I said I was and deep down I wasn't for a while. There just beomes a point when 'you know'. I don't think you sound like your there yet personally your just having a tough time and you may thinkt that quiting will take that pain away. It won't until you know your done.
Hang in there bruv, go for a run or do some exercise, I always find that helps. Clears the brain, get the good chemicals flowing round your head and makes decisions easier for me.