It sounds like this is situational.
Please, as someone said, don't rush into Sertraline.
There are side effects potentially.
This is my view on it, and I won't be offended if you don't agree.
I feel it can be really hard as a mum to honour your own needs.
Sometimes doing something 'for yourself' can feel like just another job to do.
I don't think you are an awful person. At all.
As others have said just think you are stressed.
Start small, and reclaim something for yourself.
It is all very well for some to say 'go and take a bubble bath' etc, but with a youngish child not so easy to do with them knocking on the door etc.
So, if you had choices, how would you want to live life?
Is it feasible for you to go away for the weekend for yourself. By yourself?
Can you get some help in?
Even someone to clean the oven (the worst job, I find) could be helpful even if you can't find a regular cleaner.
Do you have 'an escape route' when things get really tough or when you are very stressed?
MIne is a small cafe that I know. I get in a taxi and go.
I sit there, and it is the only, only time that someone serves me up a meal I can have a grown up lightweight conversation and don't have to wash up afterwards....
Get the jist. That kind of thing...
Please don't view it as your fault. Just you are too stressed and need to carve out more space for yourself.