Get out of the habit of trying to understand the reasoning for why everything happens to you. Accept it as best you can and decide to move forward with your life. Learn the art of letting go. http://www.breathofoptimism.com/stop-trying-to-figure-everything-out/
This sounds like the garbage that was fed to family members a few years back. The word toxic gave it away. I say think for yourself and stop letting people dabble in your brain. Families are often dysfunction and you my dears are just as toxic. Same blood
Forgiveness is the key to happiness because it benefits you a lot more than it benefits the person you forgive. If you truly want to be happy, then acquire and practice the art of letting go and forgiving.
"life is a balance of holding on and letting go" - Illustration depicts a caterpillar holding on to a branch which will inevitably become the butterfly sailing above... minimalist print by Ryan McArthur