You sound charming @nosmartphone. You're 'quite anti-abortion' but you consider abortion just about good enough for the OP, after tut-tutting at her?They brought this on themselves but, as tends to be the case, the OP as the woman is in the way more vulnerable position.
Sterilisation is much worse than vasectomy; getting the surgical solution really was up to him. And while it's nice for you if you always know when your fertile days are, it doesn't work like that for everyone. Besides, we don't know whether they used contraception or not.
OP - tbh it sounds to me like your relationship is probably over either way. The fact that your husband knew that you struggled with the last abortion, failed to safeguard against another pregnancy and now is pressuring you again to abort sort of dooms you as a couple. He'd have to change a lot to save you.
So the main question is: can you face being a single mother of five? If not, then either you abort and split (the 'cleanest' solution), or you abort, stay together and you 'get over it' (a challenge, mostly for you), or you don't abort and (try to) stay together. In that case, he may still leave, or you may have your five kids in a very high-conflict situation. This last result sounds pretty awful.
I sort of hope that you determine you could face being a single mum of five and go on to have a happy solo life with your brood. In that case, you're made of sterner stuff than me.
Of course it's possible that you husband 'comes round' and stops being the worst kind of patriarchal shit about this. Likely, it is not.
To start with, I think you need to tell him (preferably without using the epithet 'patriarchal shit', inviting though it is) that the choices he's made around birth control were really not OK, for reasons you can find on this thread, and that he has no right to pressure you now. Make your further choices based on his reaction.
It's a crap situation to be in OP, I'm sorry.