Just before 10 p.m. Tuesday, Houston police said the man used a concrete paver to break a glass patio door of his ex's apartment in the 11600 block of Gulf Pointe Drive.
Police said his ex-girlfriend was inside with her new boyfriend.
"He decided today, I guess out of jealousy, he took a concrete paver, he bashed in the back door patio window," Lt. R. Willkens said. It was a door with a lot of glass on it. He busted it and went into the apartment."
Investigators said once inside, he chased after his ex-girlfriend, and that's when she grabbed a pistol and opened fire.
He was shot twice in the legs and once in the stomach, according to police.
The man ran back through the door he broke and was later found collapsed nearby, police said. He was taken to the hospital and is expected to survive.
Investigators say he will likely face charges for the break-in. Meanwhile, the ex-girlfriend is not likely to be charged, police said.