You are not alone Barbara (dealing with a nasty mom). At the moment, my mom is having a temper tantrum *sigh. It's like dealing with a 5 year old that is legally allowed to live alone and make bad choices....then blame and hate you!
Ok.......it is never easy....but if YOU don't change.....then nothing else will change and you will continue to feel bad. So change means to stop expecting your mom to change....or your siblings.
Once you decide that NO ONE will treat you bad or make you feel inferior/bad.....then you have the choice to do something different or stay stuck. I too stayed stuck for years....hating conflict or "rocking the boat" so to speak. With a lot of therapy, I was able to stop the cycle and move out of my pain. It took a lot of trial and error to get it right. Boundaries are so important. "NO" is a very helpful and important part of living a happy and successful life.
My mom is having her tantrum as we speak (she is not speaking to me and is angry becuz I placed a boundary and it's sticking regardless of her tantrum.....that is HER problem).

Also....our brains are made up of plasticity. We are able to make new pathways and reroute our thinking and routines. It takes work on our part, but it is a reality.
So we become aware of our thinking. We examine and question our thoughts (i.e. why do I think/believe that? How can I change? What changes need to occur to make my life different?) and consciously interrupt the unwanted thought and replace it with a counter thought and action. It will not happen over night, but a continuous action will become a habit in about 28-30 days. So for the next 30 days become a VERY conscious thinker and interrupt and change your thought pattern (actions too).
Happiness can NOT come to you through others.....it comes from within yourself. Relying on others to bring you happiness will be short lived and come with a lot of disappointment and fall short of how you expected the outcome.
I'm not trying to be mean, but trying to point out a path to aide you in helping yourself.
It is good to watch funny movies.....listen to comedy....and do things that make you feel good. However, at the end of the day.....only you can make happiness a permanent part of your life.
Take care of YOU. This includes getting the proper rest. Eating good food and staying hydrated. Getting out in nature (in the winter, look at beautiful landscapes and nature in travel magazines or other media that is available to you). Nature is so important in calming and re energizing yourself.
Take walks when you can and appreciate the nature around you. Do deep breathing while looking around you and finding appreciation of all that you see and have (counting blessings).
As much as you can.....ignore your mom's negativity and others as well as limit your visits with them. Surround yourself with positive ppl. Check out the positive ppl at meetups or events and find out WHAT and WHY they are naturally happy :)
I remember a nurse from a stint I did in rehab many years ago that said it takes "action jackson"....lol. I would like to reiterate that......no one else can do it for you. It will never happen unless you take the steps and help yourself.

I will stop for now as this is a lot to take in and I hope that you read this and consider taking the action to move out of your pain. Life is GREAT (despite my nasty mom) since I chose to make changes. It was worth the work I put into it. I don't watch the news or read it becuz it feeds fear and the news ppl are looking for ratings and don't care how it scares ppl.
I have some GREAT things happening in my life and I never thought it possible....but it's a reality and fun!

Take care of YOU.....becuz no one else will (fact).
(((((((((((((((((Hugs))))))))))))))))))))

MsBlank. I think you said it all. I love the breathe exercises. It helped me to get back to me and shut up the shitty committee arguing in my brain.

I have a little book called Letting Go. I would read the positive affirmations and then journal about it. It changed my life.

Take care of yourself first. You are the most important thing.

I will be staying with my mom for a few weeks coming up. I will be taking care of her and her husband who has Alzheimer's. I know that my mom will be delighted, not so sure about him. I will probably be back here asking for help :)