You're a little lost, let me help you.
No one is saying the President didn't know Netanyahu was coming. He did know. At the end of January the White House released a statement saying it was going to snub Netanyahu's visit. Why?
Because the Republican Congress did not consult with or seek approval from the President when negotiating an invitation for Netanyahu to speak in the House Chamber. This breaks precedent and was also designed as a political power play against a sitting Democratic President. Why did the Congressional Republicans do this?
The past couple of years, the White House has been negotiating a peace treaty with Iran to cease any nuclear weapon program going forward in return for lifted sanctions. They have come very close to closing a deal, but the details have yet to be ironed out. During these negotiations, Israel has declared discontent because they see Iran as nothing more than a terrorist nation that wants to destroy their Zionist state. Israel has no interest in "talks" and would rather see Iran suffocate under sanctions or military action. Republicans side with Netanyahu because they are diehard Israeli supporters. No matter how hawkish Israel can be. This tension between the White House and Israel, because of the Iranian talks, goes back a couple of years.
There is a reason why the White House hasn't invited Netanyahu for a visit. Because tensions are high, and the White House feels Israel is undermining these peace talks with Iran and influencing the political processes of the United States. Israel is "stepping over their boundaries" when it comes to US policy making. Republicans see this, and because they so desperately want the President to look like a lame duck, they orchestrate to have Netanyahu visit the United States behind the President's back. Not only is he coming to visit, but Republicans are allowing Netanyahu to use the House Chamber to spew his anti-Iranian rhetoric.
This is why the White House and ~50 Congressional Dems snubbed Netanyahu's visit and speech. Because it was orchestrated by Reps as a political power play to undermine the President's peace talks with Iran.