Spending time with OH family (and him with mine)

How much time do you spend with your OH's family? How much do they spend with yours?

This situation is really playing on my mind. Up until 2 years ago OH and I lived quite far from our families (though we had my son and 1 step daughter living close to us) This was fine by me....a few times a year we would travel to visit my family (mainly my sister - 13 hour round trip) and also to visit his other son and daughter (all adult children, all living at least an 8 hour round trip away).

However, recently both his son and daughter have moved back close to us (following marriage break-ups for both of them) and they seem to be on the doorstep all the time wanting help. I'm starting to resent them being around so much. In particular I do not get on with my step-son as he treats his father (my OH) like a personal slave, borrows money which is never returned and spins lie upon lie. It hurts me that he treats his father like this (actually he would treat others like this if they would allow it but no-one else will) so i don't wish to spend time with him anymore (is that reasonable?)

From my husbands side he dislikes my sisters husband (my sister is truly my best friend) he see's my brother in law as a show-off and a snob (i don't see this..they are very well off and my b-i-l will speak his mind) i really think my husband is jealous in some kind of way about how much financial success (and success in most areas of life they have had, my position is that I am pleased for them that they are so financially secure and have a lovely family)

The up-shot of all this is that i now find myself making excuses not to go to his children's houses for get together's (I just don't enjoy it) and he has made it clear he no longer wishes to visit my sister (or any other member of my family) his excuse being that they are too far away and he doesn't like b-i-l.

All of this saddens me, its clearly not a healthy way to behave on either of our parts...and yet in every other way I know we love each other and get on so well together.

I'm not really sure what I'm asking but wondered if any of you have any knowledge of this kind of behaviour in your relationships, and how you handle it for the best.