There is a huge backstory to this regarding DHs parents and their behaviour towards DS. We have had no contact for 6 years. This was their doing but they swear blind it was us.
We have had a lovely 6 years, have had a DD since that they have never met or shown an interest in. We have never bad mouthed them to DS who is now 10, he knows they exist but isn't interested enough to ask about them.
DH is in touch with his brother who lives overseas. He stays impartial enough but tries to shoehorn them into the conversation when he's over here.
Now. This is where i am in the wrong. Me and DH know each others FB passwords. No secrets so no need to hide anything. SIL got married last week so BIL is over. He wants to come visit next week. They communicate by PM on Facebook. I dont know why but i went into DHs messages. Sheer nosiness.I've never done it before.
6 months ago he asked his B for his Dad and Sisters mobile numbers as he "thinks of them often". He then states that he will put them in his phone under aliases thus being "cunning". His brother then answers with good idea, very cunning. 
I have never told him he can't see them but since they admitted 6 years ago they can't stand me and maintain that I am the root of all problems this just tells his brother that I'm the cow stopping him seeing his family, confirming what they think of me. I'm gutted. Dh says that although he has the numbers he hasn't been in touch with them. His reason for asking was that they're getting on and how would he feel if they died and he hadn't contacted them. I get that but after how they behaved in the past to both me and DS I can't get past it and can't understand how he can.
I know this is rambling and that without backstory it's hard to comment. I may regret posting, but am I over reacting? Should I feel, i don't know, betrayed? cos I do. I'm not a cow. I only ever wanted to get on with them. Do I let them back into my childrens lives after they pissed off out without a backwards glance?