Minor League baseball player speaks out after family killed in triple murder: 'My life as I knew it is destroyed'

Minor league baseball player Blake Bivens has broken his silence two days after his wife, child and mother-in-law were killed at their Virginia home, allegedly by another family member.

Bivens, a 24-year-old pitcher for the Tampa Bay Rays, posted a photo on his Instagram page late Thursday, showing his mother-in-law standing beside his wife who's holding their baby son. All three were smiling.

"Two days ago my heart was turned to ash. My life as I knew it is destroyed," Bivens wrote in a lengthy caption accompanying the image. "The pain my family and I feel is unbearable and cannot be put into words. I shake and tremble at the thought of our future without them."

Joan Bernard, 62, Emily Bernard Bivens, 25, and 14-month-old Cullen Bivens were found dead Tuesday morning at the family's home in Keeling, an unincorporated area near Virginia's southern border with North Carolina. Matthew Bernard, 18, was arrested later that day following a manhunt on three counts of first-degree murder for allegedly killing his mother, sister and nephew, according to the Pittsylvania County Sheriff's Office.

A firearm was used in the killing and a 911 caller reported a shooting. The causes of deaths have not been confirmed, authorities said.

In his Instagram post Thursday, Blake Bivens wrote moving tributes to each of his slain family members.

"Emily, my sweetheart, you are the best wife and mother this world has ever seen," he wrote. "You made me into the man I am today and you loved me with all of my flaws. You brought our precious baby boy into this world and made our family complete. Your love and kindness changed countless lives, including mine."

He continued, "My sweet little boy, dada loves you so much! I can’t breathe without you here. I finally understood what love was when you were born and I would have done anything for you. You have changed my life forever, you are my reason why. I long to hold the both of you again in heaven. I’m so glad you are with all your Great-grandmothers now, I know they are eating you up. This earth did not deserve either of you; you were just too wonderful to comprehend."

"Joan you were the best mother-in-law anyone could ask for," he added. "You loved your family more than anyone I’ve ever seen. You raised the most wonderful girl in the world. I’m so glad y’all are still together. You were the best Nana this world has ever seen and I will never forget you."

Bivens also expressed his gratitude for the relatives, friends and colleagues who have shown him support in the wake of the tragedy. Bivens said he and his father-in-law "will get through this together as a family" and "will not let the devil win."

"Thank you God for giving me the most wonderful family in the world! I’ve been blessed beyond belief," he wrote. "I’m not sure what is next for me, but I do know God has a plan even though I can’t see it."

ABC News' Emily Shapiro contributed to this report.