I am so truly, truly sorry to hear what you are going through. I am also terribly sorry to hear that you were, or are, not well. You have a hell of a lot on your plate. The first thing to remember is that you are not alone. And truly - congratulations and seriously well done for having the strength of character and belief in your own values to voice your polyamorous preferences to your family.
You have asked for personal experiences, to help you feel that someone relates to you, so I will share some with you before I offer you advice.
My situation hasn't been as severe as yours at all; but it hasn't been as wonderful and supportive as I aim to be with my daughter if she grows up and comes to me, petrified of what I'm going to think about something.
My girlfriend's situation was worse than mine. For a while, things between her parents and her were very frosty indeed. My girlfriend was in pieces for a long time. Even as adults, we subconsciously need our parents' approval more than we realise. The lack of it can send us into complete depression. My GF would take me on family days out, where I was in the company of her mother. Her mother literally pretended I wasn't there - looked right through me; didn't address me, etc etc. She told my GF that she felt it was no better than adultery, that it was unnatural (both the poly and the bisexual part)... all of the usual excuses people come up with to justify their own discomfort. Her sister was much like yours - she defended the reaction of their parents and said that GF had to understand their perspective. GF's Dad didn't like it either - though, in comparison, he was very nice to me. We met him for dinner and he just came straight out, when he and I were alone, and said that he didn't agree with it, but I'm a human being and he had absolutely no issue with me personally. His wife, however... hahaha... well, she says that I am not welcome in her house, because she wants to protect their teenage boys. And yes... she has gay friends too. It's funny how many outwardly liberal people freak out when something liberal lands on their actual doorstep.
One thing to bear in mind is that everything seems worse when it first happens. Give things time to settle. After a year, my GF's family are easier to deal with. More importantly - my girlfriend realised that if constantly reaching out to (and trying to persuade) her family was going to cause her rejection and hurt, she had to stop doing it.
That being said, now really might be the time to ask yourself if you really do want to continue to seek the approval of your family.
The 'blood is thicker than water' thing... it's nonsense. We have biological ties to our parents that affect our psyche as we develop. That is as far as it goes.
Counselling could actually help, with deeper issues. We are all effected by our parent-child relationships. They can manifest in limitless ways. For example, my own mom hasn't been as supportive or loving as I would like, about my poly pursuits, the fact that I mostly like women, or other things in my life. This got me down for a while. I also realised that it had an effect on my adult life and relationships. If therapy helps you uncover some issues like this, it can help you mend them.
My GF's parents were both very irresponsible when she was growing up. She has termed them emotionally abusive, for certain. She had therapy during her twenties to help her let go of the responsibility she felt; particularly towards her mother's reactions, feelings and behaviours in general. YOU are not responsible for the absolutely diabolical reaction of your family - they are. And more shame on them - for you are the truly enriched one; whilst they are lacking in many things.
One thing that did help my girlfriend, when she was really, really struggling with her parents' reaction to poly, was an analogy I gave her. She couldn't understand why they were so prejudice. This, in turn, naturally made her angry, confused, distraught. Again, in turn, it made her do what we all tend to do - try to persuade, teach, enlighten the ignorant party. What we don't realise is that when we do this, we actually look like we are trying to push them - and this can make them recoil even more. Even worse, and more importantly, we end up feeling more and more rejected.
The analogy I gave my GF, I will give to you. Imagine now, in your own mind, one thing that you might be prejudice about, or that you might find uncomfortable. It could be the idea of sitting around a table with a religious cult. Or a bunch of coke heads. Something else that doesn't land in your comfort zone. If you judge nothing, go more extreme. Think about how you'd feel sitting in a room full of convicted criminals. You think people in prison have done wrong, right? Even if you were open to hear their stories, even if they were wrongly convicted, even if they had good reasons for doing what they did and you came to see things differently, would you not initially judge them, based on your own moral code? And based on this, would you not feel uncomfortable?
For some people, homosexuality, polyamory.. anything that deviates from *their* idea of normality... really, literally, feels as wrong to them as murder or theft or some other kind of crime. It doesn't fit with their moral beliefs. Now, of course, you aren't hurting anyone. But that isn't the point. They think that your way of life is *wrong*. And this makes them uncomfortable.
If you can get inside their heads that way, it can help you find understanding - at least in terms of why they are reacting this way towards you. It could help you realise that none of this is your fault - it's all them. It's all to do with them.
Their extreme reactions mean that they are ignorant and, sadly for them, incapable of understanding. Incapable of real love. It is sad for them - take stock of how dark their lives are in comparison you what you have. You have real love - you have it twice, with two wonderful partners. You have self-conviction. You have compassion; you tried to keep your family together. You have loyalty, you have honesty, you have many wonderful treasures that they are void of. Take comfort in that; because it really does mean everything.
me: open poly (31, female)
GF: (41, female) my long-distance, long-term partner
Earth: (35, female) newly dating
Hubby: (38, male) GF's husband
Garcon: (28, male) GF's boyfriend/submissive
“Peace comes from within. Do not seek it without." ~ Buddha