Apologies for the length of this, but I want to avoid drip feeding if possible...
I have a great relationship with my DP and also with my DM, but, as with many inlaws, they really don't get on with each other. In fact, they fell out properly when DS1 was about 10 months old and I found it very difficult as I got completely stuck in the middle trying to mediate between them... after that they didn't see each other for about 2 years - I went once or twice a year for a long visit to DM with the kids but DP stayed at home.
Over the last couple of years things have improved and DM has been over to stay with us several times and although they still aren't keen they seemed to manage to tolerate each other for the sake of me and the kids. However, now it seems to be all boiling back up again... DM is visiting as DS3 has just been born and pretty much every day there is some kind of unpleasantness.
The problem, I think, is partly cultural and partly just personality clash. They are both people who are very set in their ways and automatically think anyone else's way of doing something is wrong if its different from theirs - but neither of them thinks they are like that! Also, DP is very direct if he is annoyed about something (in a way DM finds very upsetting and rude) and DM is completely insensitive about stuff that is clearly likely to set him off (then gets very upset when it does). She thinks he is aggressive and controlling. He thinks she is rude and over-reacting.
Lately the issue has been cleanliness: DP and his family are borderline obssessive about domestic hygiene. DM has a far more relaxed approach. Obviously I was raised by DM and so am not panicking about dirt, but on the other hand I quite like things clean, especially as we have a new baby at the moment I think it's quite normal and sensible to be a bit careful about handwashing/keeping things clean around the house. DM takes exception when DP asks her to wash her hands when she comes into our house (although there's no way she'd do it if he didn't) also she really doesn't get how disgusting it is for him that she has a day old used cloth hanky in her pocket. Also at dinner this evening she passed a drumstick she's already eaten part of to the 2 year old to finish... and she'd think nothing of using a tissue she'd already used herself on the 2 year old or the 4 year old ... to be honest I'm totally with DP on all of this being wrong/revolting, although on the other hand I grew up with this kind of stuff seeming normal and knowing we are all healthy and all survived so also think it's fairly harmless really - just I wish she wouldn't! But on the other hand I know she means well and she's lovely in lots of other ways and I hate that this is making her feel so unhappy/uncomfortable around us - but i wish she'd just think a little bit!! And as for her relationship with DP, this is just 1 example - even if we got the hygiene issue sorted, he would find something else to be annoyed about.
I have tried talking to both of them and tried to give them tips to help them understand each other a bit better but it really hasn't helped ... and I'm starting to think the best plan is just to keep them away from each other... I just don't have the energy to try to fix this any more, I am so sick of being stuck in the middle ... I used to find it upsetting, now it's just sort of funny except for neither of them sees it that way.
I don't want to sacrifice my (or the kids') relationship with either of them, and I don't want to ban DM from visiting us (or for DP to have stay out of the house when she does) but I don't know if I can stand the atmosphere of of what's it's like when she's here.
So, thanks anyone who read all the way through this! And, from your own experience regarding inlaw relationships, should I just let them fight and stay out of it, or should I go back to only visiting DM at her place without DP? I think she'd be devastated though, if she thought she wasn't welcome at ours.... Any suggestions welcome.