Hi Megan, welcome to the Dharma Overground. (To avoid confusion, I think it would be best if you set up a login here for yourself.)
The kinds of tension you describe sound very familiar to me. Family life and solitary pursuits are not easily balanced and integrated. Some thoughts:
There are several meditation "postures": sitting, standing, walking, and reclining are the traditional four. You mentioned hiking (no talking during walking meditation, though).
At night, our daughter loves "being quiet" for a few moments and "saying good wishes" - after the bedtime story and talking about the day's events, of course! We also "smile at the new day" with her first thing in the morning. Kids tend to enjoy such little rituals, and while short (a few moments), they are examples of how Metta practice can be integrated naturally into family life. There isn't even any need for Buddhist terminology.

When I manage to get up early, I can meditate without my family feeling "left out". Ditto for the time on the commuter train or bus, and for the lunch break.
Also, after reading Daniels book, I got really enthusiastic about my great spiritual quest. I meditated like there was no tomorrow, which resulted in me causing my wife grief similar to what you've been experiencing. I made quick progress in my meditation, and plunged into the "dark night" (see Daniel's book) around last Christmas. Really, really bad timing! I've slowed down a bit since then, tried a more balanced approach to the three divisions of the Noble Eightfold Path (everyday life, concentration, insight), and I like to think my practice and family life are more integrated and natural now.

Even finding a graceful mode of practice takes practice, it seems.
Cheers,
Florian