How to get session variable after forward from node?

I am forwarding from nodejs to an html file through code:

res.sendFile(__dirname + '/' + fileToServe);

where fileToServe is an html file. I notice that when I do this, the previous code I had in my .htaccess to interpret html files as php files does not work anymore. Therefore, I can't include php files, or php code for that matter. All I need to do is get a session variable from php. I have thought about running the php file via node through something like,

  if(fileToServe == 'index.html'){
      //php parse
    var exec = require("child_process").exec;
    app.get('/', function(req, res){exec("php index.php", function (error, stdout, stderr) {res.send(stdout);});});
  }

and then get the session variable in the mentioned "index.php," but the problem with that is that the php runs on my server, not on the client, where I need to get the php session variable from, and store.

If I simply change the index.html file name to index.php, and try to do res.sendFile on that, nodejs doesn't understand it, and therefore can't serve the file.

Any ideas greatly appreciated!

thanks,