Hi Patti, and thanks for your question.
I'm glad that you've already spoken to your husband about your concern regarding your non-existent sex life. It's a shame that he hasn't taken more of an initiative to try to resolve the problem, but going to the doctor and getting Cialis was a move in the right direction. I think, at this particular time, it would be a good idea for your husband to go back to his doctor, or a specialist, and have some lab work done, to determine the cause of his lack of sex drive and the E.D. you suspect.
Yes, if he drinks on a daily basis, not only can this contribute to his decreased sex drive, but it is not recommended to mix alcohol with medications like Cialis and many others. He may need professional help to stop his drinking, as well. If your husband is or ever has been on anti-depressant medications, this can also decrease and/or eradicate his sex drive.
I understand your frustration, and if you are married and love your husband, you deserve a satisfying sex life; however, I would not recommend cheating, due to that reason. It seems that you've put a lot of thought into this, and it's on your mind a lot, which is normal, if you have a good libido and your husband does not.
It would be a good idea for both of you to begin marriage counseling and try to make physical and emotional changes which will benefit you both.
There are other ways to enjoy each other sexually, in addition to intercourse, if your husband is not able to achieve and/or maintain an erection; he can pleasure you in other ways, so you can achieve orgasm, if that is your goal. Just laying together, undressed, exploring each others' bodies intimately, and achieving pleasure without actual intercourse, can be a very fulfilling experience for you. You might also consider using sex toys and aromatherapy/exotic massage oils and lotions. If he is totally not interested in doing this, then, again, the counseling and medical evaluation/treatment should help. I think you'll find this informative:
I hope things improve for you soon!