This sounds awful! I'm so sorry you're struggling. And it's like the more you force on the mask the worse it must make you feel. When they should help you they're adding to it. Some people just don't understand and they don't want to it's hard to know what's going on and it sounds like you need someone for support or to talk to, so that it's not all weighing on you. But try to look after yourself, go as much as you can but if you can avoid a few occasions if it relieves some stress so you don't get overwhelmed then pick and choose those moments but if you decide to not go remind yourself that it's because you need to look after yourself and that IS perfectly acceptable so do it guilt free. If you as much as you personally can be then that's the best you can do, any more is going to stretch you and cause you stress and may not be the best way to enjoy each other's company anyway.
I recommend talking to your family, I personally think 1 to 1 is best because if you feel like it's you addressing all of them that can be quite daunting and also it's not neutral territory. Maybe plan a few points you want to raise, but really try to not have a go or get angry or overwhelmed, even though it's easier said than done. It can be tempting to bring up previous things they've done, but for the better of the situation it's best to focus on what you would like to happen, that's very important. Good luck