I'm definitely not commenting on your situatio OP but this stuff does make me think....
There are far far more negative threads/comments about MiLs on MN than there are about DMs.
That means that either the women who are MiLs are somehow more difficult people as general notion or that the MiL/DiL relationship is the issue, which I think is far more likely. Mothers of men are no more likely than mothers of women to be an awkward group.
I think the idea of 2 women 'competing' for who will have more importance in a grown man's life is sad really. I think it's a lot about pulling rank and being queen bee.
It's unnecessary though, surely, because in healthy relationships any notion of 'competition' is pointless. Why would a MiL not love the woman her son chooses and with whom he is happy? And why would a DW not love the woman who has nurtured and shaped the man that she loves?
I just hope beyond hope that my sons find partners - of either gender - who have filled their boots on as much love as they could possibly need as children so that they understand that love isn't a finite resource.
It's a shame that MiL/DiL relationships can descend into 'he's mine - no he's mine'. They are different relationships. This is understood when it's a woman and her mother so why not when it's a man and his mother?
And all the 'she said...she did this ... she did that' on either side? Well what good does that do?
I think it's sad.