Think i should take a Plan B...

I’m 19 and i was seeing a guy who has a three year old and the baby momma recently came to me and showed me all sorta of evidence that they still talk and have sex... he came in me Monday and Tuesday night (yes it was irresponsible as fuck I know) and I got a positive ovulation test yesterday when i usually don’t ovulate for another 10 or so days. Last month I didn’t get my period (not pregnant) my cycles are off because I have Pcos. She told me he used to cheat on her and all this bad stuff about him and I reallyyyy don’t want that life but I haven’t worked in over a month and I don’t have the money for a plan b... i don’t know what to do. There’s a big chance I won’t get pregnant because my cycles but with my luck you never know... I made dumb decisions and now im fucked