Since everyone has covered everything else, I want to make a comment on the bipolar aspect of this.
I have bipolar. I was diagnosed about 3 or 4 years ago. I STILL struggle with it and even though I am on a good med regimen that keeps me fairly stable, I STILL have bad days. It is HIGHLY unlikely that the first med regimen will "fix" bipolar. It has to be adjusted and the only way that can happen is if H is ready to face the bipolar and communicate properly with her doctors.
I know you love H, and it seems you love K, but H really needs you, she needs a support system that she can trust isn't going anywhere. I have been where she is right now emotionally, happy that the meds are making her feel better, worried that the new found diagnosis will mean the end of you, that she is too difficult for you to love. Likely frustrated with herself for not being "normal". Its a whirlwind of emotion and most of it is negative.
It may take years for her to be 100% stable. She may never get to 100%, especially if she does what a large percentage of newly diagnosed bipolars do, and thats come off the meds because they feel better (and because they dont want to think of themselves as sick). She has to instead talk to her doc about what still doesnt feel right, she has to identify her moods, watch for signs of re-occurance, and mange her illness on a day to day basis, maybe even an hour to hour basis. Things are always good right after a med change, its kind of like washing with a new shampoo, it always seems to make your hair cleaner for some reason, but eventually, that shampoo builds up on your hair too and it takes a new shampoo to make you feel that clean again. Eventually, she will have an episode, and you have to be ready for that.
Encourage her to read about bipolar, both medical books that explain whats happening and personal account books that will let her know shes not alone. Every bipolar book has a "family and friends" section that will help you cope, but dont just read that section, the whole book is full of good information for you.
I have read and recommend the following:
Bipolar survival guide
Im not Crazy, just bipolar
- a really good personal account
there are the first 3 that show up on amazon when you search "bipolar"
I have read a lot more, and own and re-read them often, especially when things get tough.
My husband has been there, through my diagnosis and before and he is fond of saying "its hard to love a bipolar, but its completely worth it"