Its very evident that Turkey knew the time and moment when the US troops were pulling out since they were already mobilizing on exactly that moment. The problem with Trump making last minute decisions that causes a massacre is something that probably should have been well thought out but as we have seen multiple times with this administration, well thought out decisions isn't one of it's strong points. We will see how much Trump can make people pay because lately the only thing he has done is make everyone pay for his blunders.
As to your second paragraph, the situation still stands, are the kurds our allies or not. This ideal you can throw blame somewhere else is a fallacy. The simple situation is that the US forces were on the ground in this area. It was the US who made allies out of the Kurds which helped us and our President claim victory over an enemy and take all the credit. What I feel for the Kurds is pretty simple. If they are our allies, then we protect them like they are our allies, not stab them in the back the moment we get the opportunity. Who cares about any other nation since it was our troops that held the ground from this event from happening. It was a world class blunder that has cost and will cost countless lives and as an American, I see no reason to seek to share the blame or find some way to include anyone else because its very evident that none of that was done.
Well that seems to make me think the decision was being talked about and made ahead of time, because if Trump made the decisions last minute, how did the Turks know how to mobilize for that exact time? It could also mean there was a leak, which shouldn't have happened, but based on America's intelligence branches and there leaks over the last couple of years, well. If a leak did come from American intelligence to make the problem much worse, then considering who's been doing the majority of the leaking, and who it typically impacts, I'd say both sides are partially to blame.
If what other countries do or say doesn't matter, then who cares about anything related to Russia? They're just sticking their noses into America's business, so who cares? Russia sticking it's nose into America's election impacted the outcome you say? Well you know what would impact the outcome of the Kurd/Turk conflict right now? Another country who's capable, getting involved and helping solve the problem. Does one matter, yet the other doesn't, even though they both effect America?
Lastly, let's say you help a newly acquired friend financially who was slightly in debt, partially because nobody else will even though their capable, and because it will likely lead to a positive outcome for both of you. Now what if that friend get's kidnapped and held for a costly ransom like a month afterwards? If you don't pay that ransom to get them released, does that make you a terrible person, considering you tried to help a little in the first place? What about this friends parents, siblings, cousins, friends, etc, who all don't want this unfortunate soul to face the consequences? Do they factor into this at all? If they decide not to help out, does the finger get pointed solely at you, because you're the newest ally who decided to help a little bit?