Pregnant 5 months after having baby

[OhGodNotYet]

I have a 5 month old son who we battled infertility for years to have. I had an emergency c-section, and although hopeful to have another in a few years time, we didn't expect anything so soon.
I feel like an idiot as we've only had sex three times in the past year, the first of which was rather spontaneous and we pulled out rather than used condoms like we did with the others. I thought nothing of it really but here I am. I'm devastated as I just don't feel like I've had enough time just my son and me. I love him so much and these were our years. I've struggled a little, been very down, coming out the other side.. I'm just not ready. Neither is my body so soon after an emcs. I know I'm an idiot before anyone tells me so. I don't know if I'm able to abort after suffering infertility and knowing I want one more, but I don't want this now. I feel like I'm in a nightmare

Sorry to hear what you're going through.
My story...
I also had issues with fertility and had a section with my first successful pregnancy.
I didn't get pregnant as quickly as you the second time (my first was 9 months) but I spent the entire pregnancy feeling guilty towards my first and feeling like I'd messed everything up.
I had a second section and it was all fine.
My children (I just have the two) are honestly best friends. They are late teens now and it's amazing seeing them get on so well.
The honest truth is that I don't know if I'd ever have made the decision to have a second because I'm not sure I'd have ever got to the point of its being the right time for the elder one.
I know you need to make your own decisions but it honestly doesn't need to be the end of the world.
(And also you're not stupid. Yes we all know that unprotected sex can lead to pregnancy but in your case it was very reasonable of you not to expect it to do so).