Concidering Toph lives way longer than Aang, as it happens in LOK, I like to imagine that, right after he passed away, Toph's only comfort was to look at their kids. "Yeah, Twinkles... we had a good life, and we couldn't have a better legacy", she would think. And by that, she would be able to smile and keep going.
Hello G! Yes yes she definitely would take comfort in her kids. And I agree she'd probably outlive Aang for a while, and obviously it's not fun to be a widow, but she's really good about keeping perspective, and I think her kids would do that for her. There are so many things she still wants to do with her children and grandchildren, and she knows Aang would've been ecstatic to witness different milestones as well. So, she continues to live her life for Aang and for their kids.
I have a bit of a ridiculous HC where Toph lives for a very long time, past 100 or so out of spite (she's like Kyoshi, just won't die). So there are always things she does to keep herself busy.
I can see Toph being the person that travels a lot in old age, visiting her kids and friends, meditating, maybe even helping find the Avatar. And after she feels like she has completed everything she wants to on earth, she'll leave.
But yeah in general I HC Toph outliving Aang, and for the most part, I see her handling the solitude okay, for the reason you mentioned above. I can also see her being a bit inconsolable, but I usually go for the former!