KPopp told Kelly to break up with him once she was pregnant, and Kelly dumped him a second time because she is such a bitch. He hung around crying a lot so Kelly just left him alone. He used this opportunity to turn paparazzi and take pictures of Kelly while she was sleeping.
In episode 49, Cameron was on their property as a paparazzi when Kelly aged-transitioned him. She had forgotten that Cameron was Diabeetus's father and that is why he was crying.
No you don't care Diabeetus you didn't even like him.