confused!

my now husband and I have been together for 10 years he has always been selfish and not romantic at all or really all that caring he's never been attentive or made me feel like I'm a priority which is upsetting.. sometimes he won't even wanna have sex with me which leads me to think the past and hes cheated on me many times in the past and so I'm very insecure. I'm constantly checking his phone and sure enough I find pictures or messages. or recently I found he has 2 other Facebook pages that he has me blocked on. I confronted him about all of it says he doesn't even use them that he doesn't have the password to them. liar..... so when we split up a year ago for a almost 6 months. in those 6 months his brother was always checking up on my daughter and I. he was everything my now husband was not. not even now that we got back together and Married. its sad but I've started to grow feelings for his brother... my now husband knows because he saw messages of ours from before and still decided to get married and make it worth... what do I do? I try not to think about it.yet I catch myself doing it all the time.