You have been misinformed, whether it be by Russian propaganda BOTS attempting to sow division and dissension to keep us a nation divided against itself (Putin wins, if that happens) or by the white nationalists and white supremacists who appear to be in control of the off-course GOP.
As a candidate for President in 2016, Jeb Bush acknowledged that the influx of illegal immigrants during the Obama administration was at NET ZERO and even went on to say this NET ZERO success had been in place since 2012 (which politifact.com supports).
On a state-by-state basis, you will discover that if someone is an undocumented imigrant, they were not allowed to be on welfare and should they try to get public assistance they will be caught, so you have been fed a line of pure bull crap...or should we say of diarrheal elephant poop.
We are still operating as a nation on the FINAL OBAMA BUDGET because there is a three-month "Continuing Resolution" in place that keeps that last FISCAL YEAR (October 1, 2016 through to October 1, 2017) Obama budget in place through Christmas (no GOP-caused government shutdown that would keep disability checks, Social Security checks, or VA incomes from going out)---a deal negotiated for the American people by former (and future) House Speaker Nancy Pelosi (D-CA) and Minority (soon to be Majority) Leader Senator Chuck Schumer (D-NY) that they were able to convince Trump to sign.
When President Obama was elected by a landslide in 2008 and then sworn in on January 20, 2009, the unemployment rate from the GOP-controlled Congress and the Bush/Cheney White House was double-digit (over 10%) and our GOP-caused DEFICIT (Bill Clinton had BALANCED our budget and left a huge $362 BILLION SURPLUS, remember) was at 10.6% of our Gross Domestic Product or GDP. By the end of the high-achieving President Obama's first term, with tremendous help from his 111th Democrats-controlled Congress, enough jobs had been created that unemployment was down to single-digit and our GOP-caused DEFICIT was cut in more than half (as Candidate Obama had promised to do), to 5.2% of the GDP and still going down. The rescue of the auto industry which every Congressional Republican except Olympia Snowe and Susan Collins opposed saved and then created hundreds of thousands of high-paying U.S. jobs, and President Obama's border security policies plus his administration's focus upon rebuilding the U.S. MANUFACTURING BASE (that the GOP had outsourced into near oblivion to "expand profit margins" for overpaid CEOs who donate to GOP candidates) by making the U.S. the WORLD LEADER in the manufacture and world-wide sales of earth-friendly green energy products created millions of American jobs! Trump's idiotic (and even insane) abrupt pull-out of both the Trans-Pacific Partnership trade agreement that the Obama team negotiated plus the utterly incompetent Trump pullout of the Paris Accord abruptly closed the new markets for American made renewable energy products in at least eight new Asian markets (built by first Secretary Clinton, then John Kerry) to counter Chinese aggression----aggression that now China can do without the U.S. countermeasures set up in the Paris Accord and the TPP, is going to have long-range NEGATIVE EFFECTS on our nation's jobs markets over the next few months.
The security of our borders was great under President Obama, but under the incompetence, dangerous volatility, and ignorance of the Trump administration on the issue of immigration, expect this security to decline significantly.