If you saw the President tweet about his plans to meet with the Taliban at Camp David and it angered you, that meant you recognized the Taliban as the enemy. That’s a good thing.
If you marveled at his naiveté in thinking we could make peace with the shelterers and allies of al Qaeda, than you and I are in agreement  here. That’s a good thing.
If you responded to this by insisting – to yourself or to anyone else – “But the Taliban are terrorists” – then you recognize that they must be defeated, period. That is a good thing.
If you accept the logical conclusion that we cannot truly negotiate with the Taliban and expect anything but a complete de facto surrender to them, then you recognize we need to recommit to defeating them and bringing Afghanistan permanently into the democratic world. That isn’t simple, but it is a good thing.
If you recognize that we need to bring Afghanistan permanently into the democratic world, then you recognize we need to acknowledge our mistakes (letting Hamid Karzai steal the 2009 election is one of the big political ones). That, too, is a good thing.
If you recognize that the Taliban are a tough enemy, then you accept that the war against them must continue – its current length notwithstanding – until they are defeated. That may be difficult to accept, but it is also a good thing.
If, by contrast, you cannot bring yourself to accept that commitment – if you’d rather the war just “end” – then Trump inviting the Taliban to Washington to sign a “peace” deal is the inevitable alternative. That is not a good thing.
If, however, you are ready to accept the hard truth from which your outrage flows – that defeating the Taliban and liberating Afghanistan are right and necessary things to do – then you must ensure both the president and his would-be Democratic challengers know it, too. You must make clear that any promise to “end the war” without winning it is, in fact, losing it. You must remind Biden, Sanders, Warren, et al, that any claim to be the antithesis of Donald Trump is badly undermined if they agree with his isolationism in Afghanistan, and that would not be a good thing.
If you really, truly, are upset by what the president nearly did, you will want to make sure neither he nor his successor try to do it again, for that would not be a good thing at all.
If that anger, disappointment, and frustration are still with you, then you know the war in Afghanistan must be won rather than ended. That won’t be easy, but it is a good thing.