I feel you, dear - I was recently dumped after 9 years when I found out my partner cheated on me.
I understand the feelings of utter betrayal and mistrust. Plus you probably ask yourself now - How could I ever trust someone again after my ex claimed to love me first and then did this to me?
But... is there really nothing left for you to live for, though? Do you have family? Friends? Maybe children? Pets? A job that you like?
Please try to think about it thoroughly before jumping into this scenario. I know the current pain is eating away at your soul - and trust me, I still struggle to stay alive every day, altho I was cast aside over 3 months ago. I'm not saying it is easy, but if there is even the slightest hope that you might enjoy life again in the future, I can only give you my warmest advice of trying to hold out until then.
In my experience, when horrible things happen to us, we are overwhelmed by the situation and the negative feelings, but oftentimes, after some time passes, we are able to see more clearly again and are able to find different solutions.
But whatever you decide to do, I sincerly hope you will find your inner peace.