After a season-ending injury at the outside linebacker position in Saturday’s preseason opener, the Bills addressed the roster vacancy Monday in the form of free agent OLB Kroy Biermann. Biermann worked out Monday morning and signed a contract early in the afternoon.

OLB Kroy Biermann signs contract with the Buffalo Bills. (Aug 15, 2016)

*Kim Zolciak is calling today one of her “hardest days ever” after seeing two of her sons start kindergarten and pre-kindergarten, and her husband Kroy Biermann leave the roost early to catch a plane to Buffalo, where he will begin his new stint with the Bills.

Biermann, 30, has played his entire career for the Atlanta Falcons, who made him a fifth-round pick in the 2008 NFL draft. The nine-year veteran has played mainly as a defensive end, but may scoot to outside linebacker in Buffalo’s 3-4 defensive front.

According to buffalobills.com, Biermann (6-3, 255) made a free agent visit to Buffalo in the spring when the free agent market first opened, but ultimately did not sign a contract with the club. The Bills lost OLB IK Enemkpali to a season-ending knee injury Saturday night when he tore the ACL in his right leg. It left Buffalo with just five healthy outside linebackers. Enemkpali (who came to Buffalo last year after sucker-punching Jets QB Geno Smith and breaking his jaw) was waived/injured to make room for Biermann on the roster.

“This has been one of the hardest days ever for me. Kash turning 4 and starting Pre-K, KJ starting kindergarten and my best friend, my everything left this morning to play for @buffalobills,” Zolciak wrote on Instagram along with a photo of her husband hugging KJ and Kash goodbye.

Biermann will have several in-laws with him in Buffalo. Zolciak’s parents grew up in the town and she still has family members in the area. Still, though, “It was hard to say goodbye,” wrote the former “Real Housewives of Atlanta” star.

The new season of her Bravo series “Don’t Be Tardy” premieres Sept. 14 at 10 p.m.

Watch a first look below: