help! New to site, need some feedback

I have been with my husband for about 3 years now and we have a 14 month old son together.  As I have read a lot on the site, our courtship was amazing.  I came from an abusive relationship and thought that I had finally found Mr. Right.  Well, since our son was born a whole new person has emerged.  He is angry, sometimes violent, started watching porn and being sexually disrespectful.  If we get into an arguement about the smallest thing I see his whole face change and he becomes this monster that is unable to be spoken to or reasoned with.  I have tried so many time to be patient and talk things through with him, but once he gets upset I just don't know what to do.  Before he would get angry and just leave for a couple of hours, now it has become where he is violent, verbally abusive and will try and break things all around the house.  It is unbeleivable scary and even our son seems to notice the change in him.

 

I want so much to be able to make this work, but I don't know how to get through to him.  I know he has been diagnosed with ADHD and does not wish to be on medication for it.  I want to know if there are any tips or helpful advise on how to deal with this and if I can address him in a different way that he will resbond better to.  Anytime I approach him about a situation, no matter how big or small, he makes it seem like I am attaching him or belittling him.  That is his favorite word, belittle.  All I do is sit there and try and think of how I can approach him so he won't get mad, but regardless of my approach things always get out of hand.  It can be for something as small as taking out the trash.

 

I have also caught him in a few instances where he was talking to people that he said he was no longer in contact with, sneaking porn and denying it when confronted, etc.  I could really use some feedback or ideas and would appreciate any assistance.  I really want to be able to make our relationship work, but if I can't figure out what makes him act this way, I'm not sure how much longer I can live in this misery.