回复：前任雇主会不会黑我？

Of course you don't want his letter of recommendation. That's for sure. The question really is, what was the basis for firing/laying off? If you have enough evidence to support your argument, you should not just leave like this. If it were me, I would fight the war all the way up until some senior management people gets involved. HR is only trying to make you go away peacefully. Hence, don't trust a single word they say.