I really applaud your effort to make a recipe, but this definately warrants a "dump it out and try again". I really don't think there is anything that can save it. Your beer won't spawn anything harmful, but it will sour. Lactobacillus is the bacteria that causes sour milk. While its used a lot in the sour brewing world, it comes from certain strains, and definitely not milk!
If you want to make a chocolate stout, cocoa powder or cocoa nibs are the best way to go. Chocolate bars contain a lot of fats, extra sugar, sometimes vanilla and milk solids for milk chocolate. Cocoa powder is merely the cocoa solids after the fat (cocoa butter) has been pressed out. Its extremely bitter alone, which is why Chocolate Stouts usually incorporate lactose to sweeten it up. Lactose can be found at any homebrew shop. It is a white powder. Lactose is a longer chained sugar (hence not as sweet). This also means yeast cannot ferment it. That means the final gravity of your beer will be slightly higher, which translates into a slightly sweeter beer.
If you haven't already done so, look for a kit from your local homebrew store, or a respected online store like Brewmasters Warehouse, Austin Homebrew Supply, or Midwest Brewing Supply.