I reckon there would be a war. We would try to make peace, but honestly, that probably wouldn't work, unless like humans get one half of the planet, and the aliens get the other. Either way, there will be casualties to be had.
But, if we were coexisting, i think the more western nations would be very accepting of them. I mean, look at all the *shudders* SJW's we have. There would be most definitely a few people who aren't accepting of them, but those people will very likely be quashed by the government.