depression???

My marriage is extremely stressful right now. My son is 5 months and my husband and I are both active duty. Things are piling up emotionally and to top it all off.....

I don't even know where to start. I have no one I want to tell about it all because I don't want to hear that I need a divorce. He downloaded a dating app, he messaged a random girl on fb to 'catch up', he was looking at 'getlaid.com', he wants to have sex but I can't do it. I don't want to because I'm so emotionally distraught over all the pain he's put me through. I know men need it like we need to be told we are loved etc. but I can't give him what he needs because I'm hurting. I don't trust him. How can I sleep with a man I don't trust? He hasn't cheated on me....yet. I know that. He never signed up for anything or made any accounts with the sites or apps, I checked (believe me, I checked). And he came clean about it all. But what's killing me is that he doesn't know WHY he did any of it. WHY. I feel like if we figure out the root we can fix it. He says he has never felt unloved or unsupported, that he never thinks to himself "I'm unhappy in my marriage". So why?????  

I can't just have sex with him to make him happy and then here I am giving everything I have. Working full time, taking care of bills, car maintenance, the dogs, the baby, the house, our ENTIRE lives and all he has to do is go to work and help out without me asking. You see freakin laundry? Do it! Do the dishes! Do it all! If I'm struggling to keep shit clean, help out! But no, he just wants sex. He doesn't ever ask for it, but he said that's what made him look for stuff he "THINKS". But how can I have sex with him when I feel so alone and hurt and unsupported??? I love him. We talked about divorce and when it came time for him to leave.....I didn't want him to go. So I took that as a sign that we should fix it. 

And I can't talk to anyone about it because I don't want my friends or family knowing about everything. I just feel so lost.

**update** we are planning on seeing a therapist. He is gone right now on a detachment and it just felt like too much weight to bear today. I just had to talk about it......I needed some kind of mental release.