Yes, you can call it stress!
The reality of having a child is that your world does get messy, but at the same time the reality of a mature relationship is that you share the mess 100%.
I would suggest that you sit your boyfriend down and explain to him how you feel about the way he treats you. Explain to him that his lack of consideration is smothering your relationship and having an effect on your son as well.
Then suggest that if he does not want to change his ways and help you with half of the work, at least he must then pay someone to do his half of the work. Then insist on him either hiring someone to clean up after him, or giving you the money so that you can hire help. You are not his servant, you are his partner.
If he does not show enough respect to you to listen and do his share, then you do need to ask yourself what you want from this relationship and what you are getting from it in comparison to what you put in.
And yes, if you can at all go to the gym, then do it. You are expected to give a lot to your boyfriend and son, but if you are too tired and stressed, then you have nothing to give.
You have to look after yourself first, so that you have the energy to look after your son and your boyfriend (always first your son and then your boyfriend).
If you stop yelling at your son and rather give him a hug and do things with him that he enjoys, he will stop nagging. But for you to have the time and energy to do that, you need the other adult in this relationship to act like an adult and also look after the needs of your son. Your boyfriend needs to hear that too.
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