We've all been there. The reason you are feeling so horrible and dark is because of the alcohol. If you stop drinking the dark thoughts will go.
On my last binge I felt so bad I was calling emergency services saying I felt like killing myself. I didn't want to kill myself, and wasn't seriously considering it, but I felt like it as I had such horrible dark thoughts. I can't quite put into words how bad I felt. It was literally hell on earth. Whereas 5 months later after stopping drinking I am in the exact same house with same life but I feel absolutely fine. The only thing which changed is no drinking. Drinking took me to hell which is why I'll never drink again.