Having loved ones that benefit from my existence is the only thing really stopping me exiting right now. I know how you feel. How old is your son?
Sounds complicated for you if you truly are a bad mother. I think most people/parents find themselves feeling that way and as though they somehow fudging it because they don't feel ready or 'qualified'. People that claim with gusto to be wonderful parents quite often aren't the wondermum/dad they think. In my experience they're often toxic. The fact you give a shit and are open to being flawed suggest (to me) that you probably do a better job than you think.
Love and kindness are the most important to a growing child. Financial security is ideal but not the be all, end all so long as they're fed and clothed. Kids can be cruel to their parents during their formative years but, assuming you provide unconditional love and kindness they'll usually come round and ask forgiveness for their teen angst. Might take a little while.
I know that's not the question. Just though it might be helpful info.
Have you spoken with anyone about this. Like a doctor or specialist. Could be some form of post natal depression. Not sure what your mental health situation is or what it is that makes you want to exit. For me it's health issues. Unfortunately mental health meds aren't what I need. They may work for you though. There are services out there specifically foe people in your frame of mind. Have you already been through that system? If not, and your issues are depression based then maybe that's what you need. Meds may help you keep the status quo for the foreseeable future. You just have to keep putting one foot in front of the other. That's the only way I manage. It's grim but it works. With the help of meds (which tbh I'm not always a proponent for) you may find yourself in a better place. I will just say, be careful how much you divulge with professionals. You can take it as close to the line as you're comfortable with but avoid admitting the desire to ctb unless you feel you might do it imminently and there's a risk to your sons well being as a result. Hope that's not patronising to say. Things get messy in even the most diligent and sensible minds when you're at that point with things.