Why should you use such block?
Just raise error there:

IF EXISTS (SELECT SpouseID from AdultInfo where PersonID = @SpouseID AND 
          (SpouseID IS NOT NULL AND SpouseID <> @PersonID and SpouseID >0))   
    BEGIN    
        RAISERROR ('Something happens that is not right' ,
                   16, 1)
    END

>Hi everybody,
>
>I'm working on an SP where I try to update multiple tables in the transaction within the BEGIN TRY/CATCH block.
>
>Now, in one particular case I'd like to generate a custom error message and then return this custom message to the client yet perform the cleanup logic (rollback, etc.) that is handled by the catch block.
>
>Do you see the way to handle the problem?
>
>E.g.
>

>IF EXISTS (SELECT SpouseID from AdultInfo where PersonID = @SpouseID AND
>             (SpouseID IS NOT NULL AND SpouseID <> @PersonID and SpouseID >0))
>-- BTW, is using COALESCE(SpouseID,0)>) is better way here? I'm using it in other places in the same SP
>
>             BEGIN
>               -- THROW an Error here
>             END

>
>and then the regular CATCH I have
>
>

>BEGIN CATCH
>       DECLARE @ErrorSeverity int, @ErrorNumber int,
>            @ErrorMessage nvarchar(4000), @ErrorState int,
>            @ErrorLine int, @ErrorProc nvarchar(200)
>        -- Grab error information from SQL functions
>        SET @ErrorSeverity = ERROR_SEVERITY()
>        SET @ErrorNumber = ERROR_NUMBER()
>        SET @ErrorMessage = ERROR_MESSAGE()
>        SET @ErrorState = ERROR_STATE()
>        SET @ErrorLine = ERROR_LINE()
>        SET @ErrorProc = ERROR_PROCEDURE()
>		SET @ErrorMessage = 'Problem updating person''s information.' + CHAR(13) +
>            'SQL Server Error Message is: ' + CAST(@ErrorNumber AS VARCHAR(10)) +
>                    ' in procedure: ' + @ErrorProc +
>                    ' Line: ' + CAST(@ErrorLine AS VARCHAR(10)) +
>                    ' Error text: ' + @ErrorMessage
>
>        -- Not all errors generate an error state, to set to 1 if it's zero
>        IF @ErrorState = 0
>            SET @ErrorState = 1
>
>        RAISERROR (@ErrorMessage , @ErrorSeverity, @ErrorState, @ErrorNumber)
>
>        -- If the error renders the transaction as uncommittable, we must rollback
>        IF XACT_STATE() < 0
>            ROLLBACK TRANSACTION
>  END CATCH

>
>I read the Help but it yet still unclear to me.
>
>Thanks a lot in advance.