As has been said already in response to your post, you should not feel any guilt over the decisions of other couples to break up. You have no control of nor responsibility for that or them. Let that unearned guilt fall away! =]

Maybe you are a carrier?

When My Wife died, all the friends We had disappeared....wtf happened?

Yes and no, we had a close group of friends years ago, only 2 couples stayed together to my knowledge, most split up before we did. And my split was 1993.

That's ridiculous - you are not responsible for other failues.

It’s not your fault that others split up.

Unless you were living with them and running their relationship and everyday life for them, I do not see how it is your fault that they decided on their own to end their relationship. As far as your decision to end your relationship, here are a couple of questions for you. Would you rather be miserable living in a bad relationship, or be happy and free? Do you live your life for you, or to please everyone else's expectation of how you should be living it? You are a freethinker and the reason that your friends are thinking that way is because religion tells them that they have to be married and that is what is expected of them. The idea of being married for life and staying in that relationship no matter how miserable and bad one finds it, is a religious concept and that concept has been engrained into society through religious endoctrination for centuries by every religion. Be happy and do you and stop worrying or feeling guilty about other people who made their own choices.

You should not feel responsible for others and their relationship. It can be so easy to get stuck in your head trying to rationalize the world. I know. It's a pitfall that can stagnate your own growth and healing.

Some people won't take responsibility even for their own actions (#45 comes to mind) then there are those who are inclined to accept responsibility for things they have no control over. Not sure what reasons/motivations are for either end of that spectrum but it is unfair and perhaps a little arrogant.

To assume you have/had that kind of control over the emotions and actions of others is not only unfair to yourself but credits you with power that no human being has. Yes, in your own relationship you probably "own" half the responsibility for how things went. Barring "deal breakers" such as domestic abuse or infidelity, most breakups deserve shared responsibility.

In the case of the breakup of your friends'relationships however, unless you took an active part in the situation, like being the "other woman" then you deserve neither the credit nor the blame for the dissolution of their union. Regardless of how your friends viewed your relationship, the fact that it ended did not cause their's to fail. Perhaps, seeing your split gave them the courage to walk away but if so, their relationship was already seriously damaged.
Your responsibility lies only with what you reasonably have control over.

You should not feel responsible for others and their relationship. It can be so easy to get stuck in your head trying to rationalize the world. I know. It's a pitfall that can stagnate your own growth and healing.

Coincidence came to mind. I would doubt that you would have influenced someone else's emotions to impress upon them to undo the embodiment of their relationship.