Its called detempering when it splits like that, and is most annoying. Means you wern't paying enough attention to it. Just throw it away, as it is now ruined.

To add a liquid to melted chocolate, melt the chocolate with the liquid already there, and you should have no problem. There should be so little heat in the system that evaporation, even of alcohol, will not matter.

If you wish to add a solid, such as orange zest, then do that to the melted stuff. Coffe beans are nice too....

PS, for UK 'catters, go to Lidl for cooking chocolate. They insist on importing much of their stuff from Europe. This means that they do reasonable 74% cocao stuff at about 40% of the price of Lindt, so you can use lots of it for cooking with, or making proper hot chocolate etc.