Although it's not immediately apparent in the film, the script and novelisation make it clear that several weeks have passed between Coop waking up and the arrival of his daughter on the station. During that period, he's had more than adequate time to learn about his son's life and achievements through speaking to Tom's son (his grandson) and other relatives.
He wasn’t altogether sure what brought him there. Only a few days
ago — his time — he had been doing his level best to return to Earth and
never see space — or a spaceship — ever again. Now — well, now he wasn’t
sure what he was supposed to do. That plan A had happened — that he had
been able to help, and that Murph had managed to go from data to…
this, was more than gratifying. It was more than he could ask. But
there was a downside to being a hundred and twenty-four. He would
never see Tom again. His son had passed almost two decades ago, and
his son Coop — Cooper’s grandson — was biologically old enough to be his
father. Almost everyone he knew was dead — except Murph.
When Murph finally appears, it's evidently sufficient to know that she forgives him, that she didn't take her antipathy to the grave and that she's matured sufficiently to understand the sacrifice he made. She (now an old lady) sends him away to live his own life.
“And everyone,” she continued, “once a child, wants to look into their dad’s eyes and know he saw. But usually, by then, the father is gone.” She gripped his hand a little tighter. “Nobody believed me, but I knew you’d come back.”
“How?” Cooper asked.
“Because my dad promised me,” she replied.
Cooper felt tears rolling down his face.
“I’m here now,” he said, seeing again how feeble, how tiny she looked. “I’m here for you Murph.”
But Murph shook her head.
“No parent should ever have to watch their child die,” she said. “My kids are here for me now. Go.”