Need a few outside opinions here girls as this is tearing our family apart.
Background: PILs and I had a great close relationship before DS was born albeit MIL being a bit needy, asking to come out on dates with us/dinner/cinema when it was just the two of us. After DS was born honestly it was like a switch flipped for PILs and me.
Everything they did annoyed me when it came to DS and I constantly felt threatened not without reason though, MIL calling DS her baby/her son, constant photos of them and DS every time they're over, badgering me to babysit/over night stays 2 months after birth, MIL cold calling to our house constantly, FIL telling me that he and MIL were coming to visit and constantly after this, spreading around her family that I had a c section even though I told her not, sounds childish but a few family members of hers are very judgemental and as I had a c section because of mental health reasons I wanted no one knowing anyone about it. I still tried to keep up a good relationship with them for the sake of DP though. To make clear I don't let them babysit because their house is a complete tip, his DM is a hoarding and doesn't clean the house, my main concerns about it are the mold, bedbugs and food strewn over the kitchen counter and floors that could attract rats and if DS gets older and I let him stay he could put anything in his mouth or catch anything, I'm not going to keep him in a bubble but mold can be serious and so can bed bugs
The next is a conflict of discipline for when DS is older, MIL believes in hitting children, we don't. She claims she will discipline DS whatever way she likes as he is her GS! 
If you've made it this far thank you! But this is where things get serious.
It was coming up to DS's christening and DP and I had agreed that he would sort out and invite his family and I would do the same with mine because of previous circumstances and my situation so I thought things would work out. Oh was I wrong, it was about 4 days away from DS's christening, MIL came to my grandmother's house (since we weren't in ours) to drop by some presents for DS, she does this randomly when we're at home aswell. She chatted with my Grandmother and aunt for a while until the fateful question "Are you looking forward to the christening?" Came up, MIL cheerfully informed my DGM and DA that she would be away on a trip to London on such a date then quickly left which I found odd but I didn't question DP until later. DP's father texted him an hour later saying that MIL came home sobbing and in tears because she would be missing DS's christening. It was in that moment I found out that DP had told no one from his family about the christening date so MIL booked a trip away to shop with her sister. We argued and I asked him how could this have happened ? Why didn't he tell them? He said with all the planning he really did forget and because things were going on at work (personal) and the lack of sleep with DS and overtime combined.
Things escalated when FIL started blaming me and my family for this, saying we had done it on purpose so MIL couldn't attend, that we knew she would be out of town which wasn't true! DP explained it was his fault but that didn't matter, my family and I were forever blamed. Soon after MIL's nieces started posting abuse about me on Facebook, in the space of a few house it had been spread around the family, calling me disgusting and pathetic and belittling me and my family, these girls are older women, not teenagers but I ignored them and went back to talking it through with DP.
This went on and on until another member of their family FIL's niece let's call her Wendy (who I am close with and knew what was going on as we had been texting about it) saw the posts and told the other two nieces to piss off and stop being so childish. This caused a fight between the three nieces, things where things were said and secrets were spilled on purpose to hurt Wendy, Wendy does not like MIL at all and since these were MIL's nieces and FIL doesn't get on with said nieces she assumed MIL had spread this secret around her own family.
She called MIL a child abuser, I'd stayed out of it all until then ur hearing something like that after having DS in the picture I needed to know. I asked Wendy what she meant, she explained to me her own mother had witnessed MIL hit her children across the head for the stupidest reasons such as walking too slow and other things.
I was disgusted and wrecked over the whole situation, what I didn't expect was for MIL to come back to my DGM's house to "talk to me about what Wendy said". She clearly didn't know what exactly Wendy had told me and went on to admit that she had been accused of hitting a child in a previous job but she can't remember if she did and if she did that she is very sorry?! I asked Wendy about this and she said she never knew about it.
Needless to say after this whole situation I can't be around PIL's and I'm even worse off with even thinking about letting them babysit. DP thinks I'm BU...could you all please tell me if I am and what you would do in terms of babysitting and this PIL situation? It's killing DP and I and ruining the moments that are meant to be happy with our first baby.
