If your going to fix it, fix it right, buy you some epoxy resin with hardener and some fiberglass cloth and redo the parts that got broke and re resin the the parts where it chipped the resin off the fiberglass. Sand it all down smooth and fill in any minor imperfections with polyester body filler (common one is Bondo Ultimate), regular bondo will work but its more brittle then polyester and your bumper needs to be able to flex some.