Hence why you were shunted off to gran's and why he is hanging out with his current shrew.
Because they're selfish, thoughtless assholes.
Do what I do. Remove the people from your life who do not matter. If they can't give a care about you, there's no reason you should keep trying. Lavish your love on those who would understand it's value and return it in kind.
Don't let this bullshit get to you. You're better than that and stronger by far. Let it go.