I am sorry for your challenges.
My best advice, and its from my limited experience... but you need to do "SOMETHING" else, I don't know what, or which... you'd have to figure this out yourself. The trick is, you need to move your heart somewhere else, and when I say this - I don't mean physical removal of your heart. I mean, your energy. Every person has a soul, every person has a temple. That heart is your temple.
I discussed this before, and I'm gonna do this now. I am in a long-term separation with someone I've known in 2003. I get heavy heart palations. It comes and go, like depression. But depression is a different energy. And you need to rattle it, move it around.
Anyway, in the last 20 years, I been struggling with thinking of someone that I liked, and loved. It was tugging at my heart for years, while trying to do everything to ignore it, and do something else. It worked for a while, but in 2018, I got round 2 after my grandmother passed. I had it a little easier than my mom, because I'm not - close. Like, I love her, and try to take care of her in the years before, but the attachment is like... I'm over here, you're over there. What's worse is I'm an Aquarius so, the aloof attitude style is bad. People think I don't have feelings, but I DO. This to me, is my way of absorbing the pain and put it in a vessel somewhere. Burying the pain.
But once you feel something and it needs an outlet, your soul needs to feed it somewhere.
When I think of my 2003 woman, I have to masturbate somewhere private, and let it go. Because that kind of love is like "I want to be with you, and mate with you" kind of love. But when it a SIBLING, you can't do that. You need to walk off the energy or distract yourself with something else. Find something to love. And replace that love with something else. I don't know what it is for you, and I can't tell you what to do but kinda guide you.