It was an end-to-end first half, with neither side able to really pull away before being pegged back again.
Westmeath registered the first score of the half before Beggan kicked his first two-point free.
Stephen O’Hanlon and Kelly traded points with Michael McCarville then landing another big two-pointer for the Farney men.
The teams exchanged a few more scores and Monaghan then moved back in front courtesy of Beggan nailing another two-point free.
Their lead did not last long as Westmeath got the first goal of the game with Whittakar’s deflected strike nestling in the bottom corner to level the game again on 19 minutes.
Monaghan edged back out in front with three successive scores, a two-pointer from Andrew Woods and two more from McCarron.
But Westmeath fought back and equalised through Kelly, who netted a second goal as he rolled the ball into an empty net.
Beggan raised a third orange flag to swing the game back in Monaghan’s favour, but Westmeath worked two more patient scores at the end of the half to send the sides in all square at the break.