Seeking expert testimony is a sign of strength. A personal relationship with a caring professional is proven clinically effective.
I believe that I can help you with this situation.
You never said how you learned about your husbands "discrete" letter to his former girl friend. Evidently it was not discrete enough.
You now know that your husband will cheat on you when he can. This is not a very reassuring thought and destoyrs your sense of trust in his honesty and in his honor, and puts your relationship gravely in danger.
At this point you must decide whether or not you wish to save the marriage. If you think it can be saved then you should get some professional help through a licensed marriage and family therapist, or if you have lack of good sexual "communication", then through a certified sex thrapist, who is usually a licensed mental health therapist with additional training and certification.
To find a family therapist near you, if you don't have a good one recommended, go to www.psychologytoday.com and enter your state and city.
Or go to the AASECT site for a sex therapist (better choice in my opinion):ASCT
(click on this link)
You may not be able to get your relationship on track, You are just beginning to get to know him, after only a year of marriage.
You may have already decided that you know enough and want out. If so, I recommend a divorce attorney, of which there are many.
Divorce is probably the best protection unless you think that you can turn this around and keep things straight.
I shall keep you in my prayers.
Elliott, MAE, LPCC, NCC, CCMHC