Not an easy task
I'm sure you are going to deal with this for a long while. You've been victimized, and your trust has been shattered. It didn't happen that long ago actually.
Are you depressed...and by that I mean "classically depressed" - you know, feelings of sadness, overwhelming hopelessness or loss of joy in life that last longer than a few days? If you are having long stretches of this after all this time, then you are dealing with depression. If any of these things are short lived, like a couple of days or less, then you are not really depressed. You are very normal. Anti-depressants are not going to help you.
Have you gone through any anger stages? While anger is not a great emotion, sometimes it is very healing. You can get angry but still forgive.
Normally I would suggest counseling, but in your case, I am assuming that you don't have the resources for this. If you are in the US, you might be able to get counseling through a social service. I have no idea what kind of quality of care this would be however.
You haven't give us a good scope of your relationship to really make a judgment. The circumstances of this event are important. You talk about needing help for just yourself, but it's hard to tell if you have communication problems with your husband. How have you dealt with this?
You are in a grieving stage, and not much time has passed. Google "stages of grieving", and you can see where you are. It could be that you are denying some of your strong feelings about the infidelity. It's hard to tell from your post.
Hang in there. Let us know more if you feel like sharing.
Molly