Sorry that you are struggling Gismo. Sounds as if you need some time out for yourself. Your daughter is home and it's the weekend. Is it possible to arrange for her to babysit your son and get yourself out of the house and go and do something that you enjoy even if it is just for a few hours. Or get your daughter to take your son out so you can have the house to yourself and enjoy the peace.
Family life can be so overwhelming at times and so much responsibility and pressure. It sounds as if you are taking on too much when there are others in the house that could help out.
Your son is very young, but not too young that he can't understand that Mummy has had enough. I was very stressed and tired after work on Friday, and then rushing to pick my son up from school. He was quite off with me and I am afraid I raised my voice and said something very harsh back. However, it was soon forgotten, he went to his room, sulked a bit and for the rest of the evening was a delight. What I said to him, gave him something to think about, and it does not hurt for them to see that we are human and not to be pushed and taken for granted.
Sometimes stamping your foot and shouting 'enough' just has to be done for your own sanity. Mothers are entitled to be listened to and to be respected. You are not a Robot. Take care of yourself Nannywoofwoof