the Iran deal was BS to begin with (and even lefties have to admit it),
Absolutely not. The Nuclear Deal was a great deal. Every independent expert said it stopped Iran from gaining nuclear weapons, and brought them into the international trade community where ongoing trade, tourism and connections with the West would've caused them to liberalise and moderate. The only people who hated it were Israelis, Saudis and Neocons who want their people in charge in Tehran so they can gain total control over the Gulf and the world's energy supply.
If the deal had remained in place Iran would now be buying Western products and being exposed to Western culture. Dozens of western airlines would've flying into Iran bringing tourists in to see that Iranians are not evildoers, and Iranians would've been exploring the world seeing that their own assumptions about life outside their country may be wrong. Domestic political pressure would have started seeing some of the more extreme laws in the country being changed (possibly the headscarf law). Iranian oil would be plentiful on the market and be reducing the influence of Saudi Arabia, the real backward state that actually funds extremism. Neocons would be losing influence in the West as everyone could see how much nonsense they were spreading about the supposedly evil Iranians was totally false.
Now, as a direct result of a chain of events that started with the US pulling out of the Nuclear deal, we are facing the real prospect of a violent conflict in Iran. I still don't think a full scale war is likely as China, which has a real strategic imperative to ensure that not every country in the Gulf is under the US sphere of influence, will step in and prevent that from happening. Even if it means stationing some troops in Iran to ward off a potential US attack. They have indicated they'll be ignoring any further sanctions or actions the US may take over this tanker "attack", and will continue to trade and invest in Iran. Which is a crucial link in the Belt and Road initiative.