Exiting Virtual Ground back to Zero Volts Reference
First: your schematic has an error.  The ground symbol under U1a probably shouldn't be there - the bus that it is tied to comes from your virtual earth supply.

I assume that U6 is your attempt to fix your problem.  That isn't the correct solution.

Look up the phrase "differential amplifier" on Google.  You can configure one op-amp section as a simple diff-amp using only the op-amp and 4 resistors.  You simply subtract the virtual earth rail from your output and you have the result you want.