The actor-dancer began his message by saying how Angeli has always been by his side.
"Through the very best and very worst of times, this woman has stood by me and for me," he wrote. "So often, she's been misunderstood and judged for her uncompromising efforts in doing and sticking to what is right."
Gary adds that it was not an easy life living with someone of his career and health condition, but Angeli was always there, loving him as a wife should.
"No she's not perfect but it's wonderful to see and know how many she's helped in very special ways," he said. "It's not easy living with an artist like me; living with the health conditions I have, yet after everything that has come our way...she's still here loving me the way a wife should."
"She is one major reason why I literally am still alive today," he went on.
The ASAP host began to conclude his birthday message to Angeli by assuring himself that his wife will always be there for him no matter what.
"There may be things in me that still need fixing up but I know that with every step I take she'll be there praying for me as she always has," he said.
"And in the end...when our finish lines are in sight...she will be there with me," he added. "I love you Angeli. Thank you for all that you are hon. Have a happy and richly blessed birthday."
The couple tied the knot back in 1984, when Gary was 19 years old while Angeli was 25.