I was in favor of Trumps election campaign because I didn't think he would actually do anything like this. His position during the election was presented to me as a temporary moratorium on immigration from nations with ongoing conflicts. That's not what we got in having people who are temporary or permanent residents of the United States being at risk of no longer being able to live in America. This is one of the most ridiculous and callous policy positions I have ever seen and I no loner support Trump.
(Assuming this isn't a troll.) Really? He was quite clear about the actions he planned to take on immigration: "Donald J. Trump is calling for a total and complete shutdown of Muslims entering the United States until our country's representatives can figure out what is going on." (https://www.donaldjtrump.com/press-releases/donald-j.-trump-...) His actions since his inauguration are entirely consistent with his statements before the election, on this and many other issues. I'm sorry you're surprised now, but you shouldn't be.
The key phrases there are "until we can figure out what is going on" (suggesting temporary until congress can come up with a new immigration policy) and "entering the country" (not affecting current residents) also his campaign made it clear that this would not apply to all Muslims but only those from regions undergoing conflict which was half true, it doesn't apply to all Muslim countries but the inclusion of nations like Iran which have no current conflicts is also problematic
"Until we can figure out what is going on" is not the language of policy, it's the language of demagoguery, and thus your trying to read it as straightforward statement of policy is a mistake. Further, Trump's willful disregarding of the facts in for instance the matter of where Obama was born, and his general willingness to traffic in conspiracy theories about various topics including Muslims should have made clear to you that he was not being truthful about anything he implied about a supposedly temporary and limited policy change while certain facts were ascertained. He's not interested in ascertaining facts, he's interested in acting on his beliefs, which are not amenable to change by contact with facts. Welcome to the world you say you voted for - with luck you will live long enough to have plenty of time to regret it.
Edit: sorry, you didn't say you voted for him, just that you supported his campaign.
Everything about this act, including the fact that the countries chosen don't actually represent active sources of terrorism and seemingly avoid harming Trump's business interests, are exactly in line with how he presented himself during his campaign.
There's a famous quote to the effect that when somebody tells you who they are, you should believe them the first time. There are some things in the world that nobody has any business being conned by.
