Mexicans, and other central Americans, have been crossing back and forth across the border for about 300 years. The hysteria about securing the border is largely nonsense, an invention of right-wing politicians to manipulate their followers.
The south-west region was Mexican territory until the war of 1848, in which Mexico lost those lands. But many Mexicans still think of it as their territory.
I am in favor of sensible immigration restrictions. But I will never participate in hating immigrants. Whipping up fear and hate of immigrants is an evil act. Negotiation is the best way to manage the situation.