This mummy can't take much more

I am not a single parent so cannot begin to comprehend how difficult it is for you to be 100% responsible for your kids 100% of the time. From my experience with my kids (which is obviously not the same as yours) I have found that when I am struggling they seem to get worse. The kids understand my struggles and it can cause them a real anxiety. When it feels we are spiralling out of control - as in they're making bad choices and I'm getting shouty I try very hard to take a deep breath and try and rationally work out if it really is a big deal or if I'm just exhausted and frustrated. I tend to try and look at each behaviour as one event as kids don't tend to think in the big picture - for example they see the thing they want and snatch it. It doesn't have any relevance that they snatched something last week as kids are impulsive and don't usually think things through.
Obviously its important to point out poor choices but what I've learnt (and am slowly trying to put into practise more often) is that they don't listen when I give them long lectures, they don't respond well to time out but they do respond to calm dialogue. For example - What happened? Did you make a good choice? What happened because of your choice? What would have been the right thing to do?

I also think its said in lots of parenting resources that if we focus on the behaviour we want then we find that they show us those behaviours because children really are attention seekers - they want attention in whatever form it takes good or bad. If they're getting reinforcement that they can make good choices (and that it feels good to be praised) then they will try and get the attention more and more often that way.

As for the anxiety - it sounds like your little guy needs somewhere to offload his worries - a teddy or a pet or somewhere to write it down so that its not overloading his brain might help a little.

I hope this helps you, parenting is hard at the best of times so go easy on yourself.

Good luck :)