I have been married for 42 years and my husband has left me over and over again. He calls me crazy and useless and he will not communicate with me in any form. I have only $400 income and he is not paying the bills. What do I do now? Even if I file divorce tomorrow, I may not have heat by the time it is final. What kind of compensation am I entitled to?

You are never "entitled" to anything. If you file for divorce, request support and the court will determine what is correct for the state in which you reside IF they rule in your favor. I would gather no children 18 or under. $400 income-per week? Month?

Maybe getting a job will compensate you a lot better. Four hundred dollars a month ? Are there children involved ?

Does this mean you and he are renting? Start calling town and state agencies regarding help with housing, heat assistance, and food stamps. Every town/city has a social worker, found in the blue pages. Many have a senior center, or senior help in a community center. You have to work for everything, whether it's welfare or benefits, and some help is local only so will vary from area to area.
When he reaches retirement, you can get some of his Social Security, unless that's the 400 you are already getting.

Definitely spousal support. The general rule is if you're married over 10 years you're eligible to receive it. If you were married for 42 years you would receive spousal support for 21 years from him

Definitely spousal support. The general rule is ...

There may be such a general rule where you are, but not in all states. Some states only allow alimony in exceptional circumstances.

I would like to see what support you have for making such a statement as "Definitely spousal support. The general rule...." We have only heard one side of the story.