I think im in some serious trouble now

I just had a baby 4 weeks ago, i havent been bleeding for over a week so last night my SO and i decided to have sex for the first time since i had baby (my doctor told me i can resume sexual intercourse when bleeding stops fyi) and my dumbass husband thought 'oh you cant get pregnamt cuz your breastfeeding' and completely came in inside me without me realising untill it was way too late.

Like be straight with me, how likely is it that it could have gotten me pregnant again?

I am seriously freaking out, we dont want anymore children, hubbs already has a vasectomy date scheduled...

I seriously cannot discribe how dumb i feel for not clarifying the whole, hey you cant cum inside me anymore, im not pregnant, so i can get pregnant again.. like, i thought it was implied... and i know, condoms should have been present but.. weve never used condoms, and the "pull out" method has never failed us.

So just tell me please, what are the chances...