I'm going to try summarise this.
In-laws family. Dh is scapegoat, SIL is golden child and everyone else caters to SIL.
I lost a baby a few years back at 23 weeks. It was very traumatic, I had to give birth watch him die slowly and I died in theatre. It was all very traumatic.
Anyways, a few weeks later, my SIL decides to confide in me that she has also been diagnosed with a bad pregnancy, apparently the baby has grown in her c section scar. Multiple talks how the doctor thinks it's dissolving itself then she tells me she had operation to remove the baby by keyhole surgery.
4 weeks later, MIL shows me a picture of a perfectly formed small baby on hospital bed and she's had a miscarriage. I was very confused as 4 weeks earlier I've been told different. Anyways still in my grief, my dh asked uncle whom works at the hospital she claimed to be at, to look after her as he's in that section. He told me nobody by that name is in maternity.
I didn't mention it at the time and SIL sort of avoided me for a long time so I thought no point bringing it up because my DH is always the bad one blah blah and it will cause too much drama.
Anyways due to recent events, dh has brought it up to his mother because he's fed up of her lies that nobody else can see.
I've been called a devil, liar etc. I tried calmly to speak to his mother who has said nobody knew until she knew, why would she lie about pregnancy loss, and that I didn't know until after. So I tried to explain my side of things and I've been told I'm imagining things, "I'm not the only one who can lose a baby"
And when I said well I have all the WhatsApp conversations at the time which prove everything I'm saying is true..
She basically said I can edit WhatsApp conversations and she doesn't want to see it, there was a funeral for the baby
(There clearly wasn't as at the time, SIL said she let the hospital dispose of it and everyone was abit confused) she also said she's sick of DH being the only one to criticise SIL as nobody else does and she could say a lot of things about me and my children but they don't out of respect 
I'm really upset because even when MIL and Dh have periods where they don't talk, I always make the effort with the children and I'm always the one who to bring dh back to mil to sort things out.
I've literally been up at 6am some days to go to their house with my children to help with things and I'm always there to help MiL and yet I'm completely disrespected aren't i?
I'm not in the wrong to never want to see them again am I?