Why don't I get it...

Okay, when I got married, I knew about this situation that I am talking about.  I knew that it didn't make sense to me and I thought that maybe I could correct it through time either before I got married or a bit after, but it still isn't making sense to me at all. 

My husband has a child from a previous marriage and pays child support as well as recently supplying half of the insurance for his son.  The mother, who by law has primary custody of their son, doesn't have their son and she receives the money from the child support.  That would be fine to me, if his son lived with her.  HOWEVER!!!  This is not really completely her fault.  It is, but it isn't.  She has told my husband that she has planned to remarry and they have a baby together.  No big deal to me really.  That is nice if it happens.  He has quite a few other kids from previous relationships.  The point of the matter is, my husband's ex-wife doesn't have their son.  Her mother and grandmother do.  And my husband doesn't get to see his son regulary.  One reason is my husband's work schedule.  He is supposed to get him every other weekend, but since he doesn't have that off, he doesn't get to see him.  Also, for Easter, my husband tried to get him for a few hours so he could take his son to see his other grandparents (mine included) and they (my step-son's guardians) said we had no right to try because they had plans when they knew my husband was gonna get him for a few hours.  They have even told my husband that they are trying to fight for sole custody (going over their own daughter to keep my step-son from her) and threaten my husband with the cops and such.  We can't afford a lawyer or anything like that and I get free legal advice from a friend of mine who is a cop but he can't really step in and do anything without getting more involved than what he really needs to.  So, I am kind of stuck.  I am more venting than anything, but would still like to know what to do.  My husband also paid money to his ex before they were divorced (just as of October of this last year) and I told him that was a really bad idea, and he found out the hard way that is was.  Anybody ever have this happen to them?  What does one do?  I want to work with his ex so we can get this fixed.  Also, every time we were supposed to get his son, they (the ex in-laws) would tell us that he was sick.  This child is ALWAYS sick.  "He has a runny nose, but no fever.  He can't go outside, he might pass out".  True for anyone, right?  Same crap happens all the time.  They tell my husband that he has no right to see his son.  Anyone please!  Help me!  If I win the lottery, I am getting the best lawyer and this won't happen anymore.  I can promise that.  Thanks for listening.