FMIL and her 1st husband divorced when the boys were in high school (a long, long time ago). From what I understand, it was a pretty bad situation. FFIL has been married 6 times total, his most recent wife is very pleasant, they had the wedding this past May. FMIL was remarried once and divorced again several years ago.
FI did not get along with FFIL for quite some time. He has been reconciling this for the past year and half or so (as long as I have known him). We see FMIL all the time, and we arevnow trying to see FFIL and his wife more often than we were. They have all been at family parties simultaneously and are always cordial.
We have been told that his parents are still going to pool together and pay for our RD, which is generous of them and I am thankful for that.
A lot of times, when it is just FMIL and I, if FFIL is brought up (usually by her), she tells me all these nasty stories about him and what he did to her, most of it having to do with getting screwed out of money in the divorce. I don't really know if she is trying to accomplish something by telling me these things, but she is definitely not shy about throwing him under the bus, so to speak.
For awhile, I kind of was like "whoa, what a jerk", but kept it to myself and never voiced that opinion. But, after having spent more time around him, he's not a bad guy. Last time my parents were in town, they went to dinner with him and his wife and told me they had a very nice time. I understand he could have done some crappy things in the past, but if that were the case, it seems to be behind him.
When FMIL does this, it puts me in a bit of an awkward spot. I obviously am not going to agree with her and sit there and rag on his dad. Then I feel bad because FI doesn't know she's saying these things, and I don't know if it would bother him or not. I'm certain she also voices these things to him. He knows his dad was a selfish prick, he's told this to me before, but I don't know that he'd be appreciative of what she says to me.
Usually I just listen to what she says and brush it off without making a real reponse. Is there something I should say to her, or just let her vent?