Legal fees in the past four years, we are at the end of our rope

That's a whole story in itself, but lets just sum it up - it's been incredibly painful for us to have this girl grow to hate us and have her vindictively act against us. It's also been evident it is painful for her, she is self-harming, BM has her on FOUR different drugs including prozac and diagnosed with bipolar and depression, and anxiety, and so on. She is failing in school, promiscuous, destroying property, and cannot seem to tell the truth - ever. We'd like to see how she might do living with us, but we have learned that is an expensive venture - we've tried. BM has no problem sharing all adult details with her daughter - including letting her read court documents, they are BFFs as BM appears to have no other friends. We feel our daughter is lost to us. In December of 2015, BM starts legal proceedings to get more money for support, and to take all health and education etc decisions away from my SO. Essentially she claims he is difficult and it is a detriment to the children.

I have even heard my 10 yr old SS say that by staying for 6 wks in the summer it makes it harder to say good bye, so it would be better if they didn't see us as much. wow. I have watched the mounting sadness in the days leading up to the end of summer, I have seen him scoot back into a corner as we all play as a family, with tears escaping his eyes, and then scoot back into the fray when he is done. Two boys who still desperately love their daddy, and one girl who I just know would be much happier if she was could just love her daddy freely.

As we approach a $50,000 price tag on legal fees in the past four years, we are at the end of our rope. Financially, it has almost ruined us, and we have gotten nowhere really. We are scheduled for mediation-arbitration in september.

The last drama-fest was SD trashing BM's home and being taken away by police. BM calls and says I'm sending her to live there - only to stop communicating a day later because SD doesn't like that Dad will exercise consequences for her latest actions, so BM won't send her and facilitates hiding evidence of the house being trashed from her husband so SD won't be kicked out. So that's likely to get worse before it gets better. BM has suggested that I, as the step-mother, should participate in med-arb sessions - but I think it's a lead in to something she has up her sleeve. Should I just stay out of it - what could she do to me? Can she take support from my income? I do not trust her, she rarely follows through on anything she says, only communicates when it suits her and stops communicating for no apparent reason. She keeps vital information from us - things like hospital stays and huge problems with our daughter.

She even sent the children to our home this summer with head lice, the shampoo to treat it, and instructions not to tell us about it. Our case is heard in Red Deer by her application when she lived in Alberta, now I wonder if we could move it back to SK since this is where they were actually divorced, and she no longer resides in Alberta. Do I participate in mediation? Any advice anyone could offer us would be greatly appreciated