You are in the right place. I think what you are going thru is "normal" for the abnormal circumstances. You have quite a bit going on besides your son..this can totally cause situational depression and I suggest looking into seeing a therapist/Dr. for help for you.
As we learn about addiction iit is only normal that we start seeing our behavior or others thru a different perspective. Your husbands drinking is bothering you now. It could be you have become very sensitive to the issue due to your sons addiction or it could be you are seeing an unhealthy pattern you did not notice before.
In any case, this didn't occur overnight and it won't be "fixed" overnight. It sounds to me that with so much going on that maybe seeing a counselor together could be helpful. Addiction puts an INCREDIBLE toll on the family (my AD is 18 and in sober living right now).Take some time to focus on your husband..the two of you have been no doubt focusing on your son and daughter for quite some time now and it appears that now attention needs to be paid to your marriage.I also suggest alanon if you don't already go.More people will be along shortly..welcome!