Accepting the unacceptable

I've been in a relationship now for almost 2 years and for the most part its wonderful. He is my best friend but I am having a very big problem with something and I'm not sure if u should accept/get over or confront it 100%. In my husbands last relationship he had a step son and he chose to be in his life he made the decision to activity engage in this child's life. Such as taking the time to go and meet with teachers about that child's learning etc. He would take this child to school before work and pretty much be everything a father would be. Also in his past relationship his ex cheated on him several times him taking her. He also worked the entire time they were together supporting her and her child well. Eventually they ended the relationship. And months later we met and r now married. All of this information I know of becausevof the stories he would tell me. Well when we met he lived in a different town and had a job and house and when our relationship got serious he decided to leave from the town he lived in and move in with me because I care for my elderly mother. I was ok with this. So at first when he got there we had several things that needed to be done because with only females there were some repairs that needed to be done that we were unable to do and my mother asked him to hold off job hunting till we got these minor repairs done first. Him and my children got along. Now its 1 1/2 later and he still has not gotten a job and he all but avoids participating in my children's lives at all. He tells me thats he has never loved anyone as much as
But yet he has no intention on supporting me like he did her and he does not make any effort to be a part of my kids lives. He won't even get out of bed and get my sin up for school but yet he took part in his exstepsons school stuff and drove him to school every morning so that child wouldn't have to get on the bus so early.
So how am I suppose to fell knowing that he took time to be in his exstepsons life and he went tobwork everyday to support hercand her child but now he could care less about supporting me or my sin like he did her and he avoids my child or being in his life like he was the other child. I want to know how I'm not suppose to let this bother me. Because it bothers me bad. Why would he do for her and her son but not for me and my son. I've tried to let it go but it literally eats me alive. I'm jealous and envious of a cheating no good ex and that makes me sick. I am not at all a bad person so why do I have to be jealous of sumone so low. Please help I am begging for sum advise other wise this is going to consume me.