Anakin had known really before his mom had said anything. After Lando's question he'd tried to find his Dad in the Force and he'd been unable to and he hadn't wanted to believe that it was true, but he'd known almost instantly that it was. They'd lost Jacen, and now his Dad, and he hadn't even had a chance to tell him anything about him and Rikki. He'd kept waiting to maybe let him get over his new memories, and Chewie, and he hadn't said anything and now he couldn't. He felt numb, and perhaps a bit ragey, but there wasn't anything he could do about it except maybe go and help his Mom.
It was always weird to him to see Leia so young - but he wrapped his arms around her in a hug and held onto her for a minute, allowing her to pull back whenever she was ready. She might have been young, but he knew she loved his Dad. Really, despite whatever hardships Leia and Han had faced recently in Anakin's life, the two of them had always been inseparable in his mind. They loved each other, and even when his Dad hadn't known quite how to show it, or his mom how to bridge the gulf between Han and everyone around him (and Anakin could hardly blame her for that, he hadn't known either), they still loved each other. They might not have had 20 years to do so in this timeline, but that love was still there.
"I'm sorry, mom," he said quietly. If it were Rikki, he knew he wouldn't be as calm as Leia seemed to be right now. Or maybe he would be externally and it would be internally that he was a complete mess - not unlike what he was right now. A calm exterior covering an interior that wanted to fall apart. Maybe the hug was as much for him as it was for her, even if Anakin was unlikely to admit that to either of them.