I have met BIL and SIL only a couple of times. DH and I visited them (on another continent) had a great time and some laughs. The last time we met is on our wedding day 3yrs ago. It did not go well.
SIL was upset that we had coincidentally chosen her wedding anniversary to get married. They had eloped years before I met dh, it upset the family at the time. Anyway, SIL asked if we could change the date. I emailed SIL to say what a coincidence! but sorry all had been arranged. We heard nothing else & were very pleased when they accepted the invite.
At our wedding SIL was rude to my parents and openly critical about the day. She got annoyed with BIL for talking to other wedding guests (his old mates he had not seen for years) instead of talking to her all night. We were oblivious to it at the time tbh, too pissed busy having a boogie! Other guests told us later.
The next day she refused to talk to us. Later dh spoke to BIL who said SIL had never liked me, she had found me offensive when we stayed with them 
. She then wrote a ranting FB post: it was terrible what we had done to her re wedding date and horrid things about DH. DH's family were supportive to me. I blocked her from FB and moved on. It upset me that DH was not speaking to his db- they have since started to email each other again.
Now they are coming over to visit. I cannot decide what to do. DH says I shouldn't meet up with SIL. MIL has already suggested a big get-together but DH vetoed this immediately. The thing is, DS has never met his aunt and uncle (they have no dc). I want to set ds a good example. But a little part of me is still fuming. I could certainly control myself and act civilly, but it will be upsetting.
If you have read this far 
, and AIBU to want to not meet up? or should I? argh, can't decide! If I don't go then DH will visit with DS but I feel weird about not being there. Please help me get some perspective.