Hi, I'd like to help you with your problem.
I am sorry to hear that you are going through this with your husband. You mentioned your husband's drinking used to be limited but now he drinks more and is starting to isolate himself from you and others. His drinking has also increased.
The effect that your husband's behavior is having on you is detrimental to you and your marriage. It appears that his alcohol use has become either abuse or dependency. This is affecting his mood and his relationships.
It is important that you seek treatment for yourself. Although it would be ideal for your husband to get help, he must first realize he has a problem in order to be willing to seek therapy. However, you do have control over your own wellbeing. I highly recommend you contact Al Non for help in dealing with your husband and how to help yourself in this situation. Also, they may be able to give you a referral to a therapist if you should want individual therapy to help you cope.
People who use alcohol often count on others supporting them and even helping them continue their destructive behaviors. If they do not, the alcohol users often become angry and make life difficult for those around them. Or they withdrawal, causing feelings of guilt. You need to remove yourself from this situation and start working on protecting yourself, building supports and seeing if you can salvage your marriage. Much of it depends on your husband's willingness to get help. But if you start the process for yourself, he may be willing to see his issues as a problem.
Some resources that may help you include Another Chance: Hope and Health for the Alcoholic Family by Sharon Wegscheider-Cruse and The Dilemma of the Alcoholic Marriage by Al-Anon Family Group Head Inc. These books can help you get a good start. There is also a good website to help you understand alcohol use. It is at http://helpguide.org/mental/alcohol_abuse_alcoholism_signs_effects_treatment.htm.
I hope this has helped you,