Just don't know anymore...

Samantha • 29. A Mom of a 7 year old DD & 1 year old DS who is our rainbow. & I have 2 Angels in Heaven. 💔👼🏼👼🏼
My Man and I have been together a little over 3 years. He's 38 I'm 25. First year or so it was like cloud 9! After that it's been one hell of a ride. And ONLY because I truly felt connected to him and that he just needed someone to be there and prove they would stay like they promised. He's had many people stab him in the back. So, I promised myself I'd never be one of those people. I have bent over backwards for this guy. Done just about all that I can to prove to him how much I love and care for him. Last year or so sex has went from amazing 2-3 times a day to I'm lucky if I get it twice a week... 😞 AND to make matters worse I find him several times jacking off to porn when I previously asked him to come give me some... it's getting to the point of where I feel ugly, unwanted, and not good enough. I try so damn hard to please him. I never deny him I always take care of him when Aunt Flo is in town. I make sure he doesn't need to go anywhere else! But he does... and Idk anymore. I'm at a loss of words or what to do. 
Yes, I've tried telling him and being 100% honest. 
Yes, I understand he works and gets tired and sometimes doesn't want to. 
Yes, I know he could be possibly cheating. 
But he always gets mad at me for talking about it. Or he says he doesn't know why he does it? 
I asked him flat out if he was cheating and I didn't see any strange reactions but then again maybe I wanna be in denial. 
I'm sorry this is so long it's just the first time I've ever reached out to get any advice for what I'm going through... TIA for any positive input!