Alcohol Damage. The damage is related to the amount you are using, the strength of the alcohol, and your sensitivity to your level of use. Alcohol damages the liver, then the brain, can damage the lining of the stomach. The nutritional/vitamin deficiencies can lead to further liver damage, muscle wasting, and neurological damage, including numbness, problems with strength and balance.
Alcohol damage. Did you say three beers per day? That amount is not a lot. If you stop now, there should be no real long term damage, especially if you don't have any underlying medical problems and have a good diet.