You need to make yourself safe. Neither attempting suicide nor blackout drinking does that for you. Each contributes to the other. People with depression that brings about suicidal thoughts are at a much higher risk for a completed suicide than the general population, and this risk again rises when alcohol is added. Drinking may lead to suicidal thoughts and behaviors through disinhibition, impulsiveness and impaired judgment, but -- and as seems the case with you -- it may also be used as a means to ease the distress associated with committing an act of suicide. Alcoholics and other problem drinkers also have increased risk for suicidality, both intentional and accidental.
There is no other advice than to get yourself to the ER. It may help to call your therapist first, but you need to get help right now.