VERY little in the Yugoslav breakup, which began last June 25 when the republics of Slovenia and Croatia voted to secede, has worked out the way those involved hoped or thought.The crisis has been uglier than any imagined - a worst-case scenario of civil war, banks emptied, resources drained, treasured churches and monuments trashed, friends and families torn apart, historic tribal hatreds awakened by manipulative national leaders talking about both "democracy" and "unity." The Yugoslav peoples don't realize how badly they've been lied to. Now the Danube city of Vukovar in eastern Croatia, symbol of Croatia's embattled independence, has fallen to Yugoslav Army and Serbian troops. The Croats are getting desperate. A massacre of Vukovar's survivors by Serb irregulars, the talk in Zagreb, seems unlikely. After the bombing of Dubrovnik, such an event (if verified) would surely require the West, through the European Community and the UN Security Council, to cut off oil to Serbia and thus the Army. After 13 broken cease-fires it seems the European Community-brokered negotiations are in a holding pattern. Both sides say they will consider a peacekeeping force but can't agree where such a force would be placed. Troop placement could ipso facto define future borders. Croat President Franjo Tudjman is getting serious political heat from right-wing elements not to concede any land. A sad note is the recent hands-off role of the Europeans, particularly Germany and Austria. The mess is proving unpleasant for them; they are tired of it. This is understandable, but they are among the European states that encouraged Slovenia and Croatia to secede in June. US warnings at the time, that secession could prove dangerous and that a federal state - in the interim - would be preferable, were scoffed at as out-of-touch. Some German diplomats suggested privately that the threat of EC sanctions against Belgrade would itself be enough to turn any tide of aggression. They and others miscalculated what kind of high-stakes game Serbian President Slobodan Milosevic was playing. Now everyone finds out - the message is written in blood. Effective intervention may have to take place through the UN. Envoy Cyrus Vance is visiting Belgrade and Zagreb, feeling out the issue of a UN force that would occupy what EC negotiator Lord Carrington has described as "crisis areas." Croatia may have to give up some Serbian-majority land. If so, and if Serbia doesn't give, a tough sanctions push in the UN Security Council by Western democracies is required.