When did "citizens" get downgraded to second class status?

Way more than a half century ago I studied the Constitution.  It didn't excite me, failing as so many of my homework assignments were want to do, and while I now appreciate the assignment, as it helps me find particular sections more quickly.  When in school, the Constitution seems quite simple and quite clear: three branches of government, each with their separate responsibilities, and a check and balances element to keep the government from becoming the threat to individual liberty that Thomas Jefferson so deeply feared.

And the purpose of the Federal Government was to defend the Citizens and the borders of the United States of America, providing for the common defense and common good.

I spent some time looking through my dog-eared copy of the Constitution the other night, looking for the Amendment that vacated that last purpose.  I couldn't find it.  That still puzzles me, because it surely must have been repealed, or somehow eliminated.  Why?  Well, because the Federal Government is now taking steps to protect non-citizens as a priority over protecting citizens.  Apparently my citizenship now grants me second class status.  I think this is wrong.  I never heard any discussion about a change.  I was never consulted...or given an opportunity to vote on such a change.  So...why is it so.

Do I hear some of you saying "You are wrong; there has been no such change, ... what are you talking about!"?  Well...Consider the following factual points:

First: our borders are "protected" inadequately and those assigned to protect the border actually help and provide aid to people "sneaking" across and into our country;

Second: our federal administrative courts and tribunals release in the general public most of those apprehended with no certainty or, apparently, expectation that they will appear at their next scheduled court appearance and with no way of knowing where they might start looking for these people who are in our country illegally;

Third: while our economy is barely holding steady and we have millions of citizens who cannot find work in their fields or with the sufficient hours that would enable them to support their families, the Federal Government now is going to allow  a minimum of 5 million people who have come into the country illegally to get Social Security accounts and work permits so that they can compete head to head with the law-abiding citizens of this country.  Our President actually is defying Congress in this step to provide greater difficulty for citizens to find work and jobs that they so badly need;

Fourth: the federal government, when presented with State activity to protect their borders, their businesses, their roads, their homes from people present in their states illegally, prohibits and takes to court those states and prevents those states from protecting its citizens.

Fifth: the federal government provides aid...paid for by money paid in taxes by the citizens of this country...to those here without legal permission.

Now, maybe I just don't understand the situation.  However, absent a Constitutional Amendment that makes citizenship a second class existence, I am waiting for anyone in what is presumably MY (and every other citizen's) government to explain why I have been told to stand still while the welfare of non-citizens has been made a priority over my, and my family's, welfare.

Exactly when, and WHY,  did the cart get put in front of the horse?