We dont have options to stop Montenegro from secession. Crnogorci were always Serbs, but 50% of them betray their ancestry. So when we add minorities of Croats and Albanians that are anti Serbia with 50% of Montenegrins that's how they won independence.
You forgot that in 90s we fought three wars, and we would probably be sanctioned again if we roll with tanks towards Montenegro.
Simply, Milo Djukanovic, president of Montenegro is a thief, corrupt politican, once Serbian nationalist, who sold his Serbian nationality and our culture and history in exchange of 50 million dollars and fake "Montenegrin" nation.