Don’t know how to fix Parse Error

Hello ?? I’m trying to add some code to functions.php for footer widgets like so

register_sidebars(1, array(
'name'=>'Footer',
'before_widget' => '<div id="%1$s" class="footer_widget <?php if($counter == 2)
{ echo 'footer_widget_last'; $counter=0; }
else { $counter++; } ?>">',
'after_widget' => '</div>',
));

and I get

syntax error, unexpected T_STRING, expecting ‘)’

on this line

{ echo 'bottom_widget_last'; $counter=0; }

am I doing this totally wrong?