Does it make sense to write "One year since my tears in heaven" when somebody passed away?

Not really. The phrase is very hard to understand. Does it mean the person died a year ago, and you are still crying? Well, that’s normal. But why are your “tears in heaven”? Why don’t you mention the person who died - don’t you mean they are in heaven?

It’s a strange and unnatural phrase. If you can explain more clearly what you really mean, we can help you find a better way to say it.