I haven't had this- but am told the vaginal operation is much better, so I hope you can get that. I do know from long experience with surgical rebuilds that impact will pop stitches and Mt biking too soon (yeah, guilty) will make a mess of things. You really do get rattled around a lot. Maybe get some slicks and ride pavement? The low gearing might be just right.
So look at it this way- no more periods, cramps, or problems big enough to get the surgury. And down time is good- little things rest and heal, your body forgets bad habits but remembers good form. That's what off season is for, and it's winter anyway. The walking sounds good, I did a lot of that as part of PT over the last three years. Call me Humpty Dumpty. It's low impact, but you can train your gait and work on form. Go to the gym and use the mirrors with the treadmill and the spin bike. And you can fool around and try some new things for the heck of it, have some play time.
It's not down time, it's fine tuning time. You can use rest and slowing down very constructively. And don't feel bad if you find yourself splat on the sofa- it's major surgury.
Get well soon

Lizzy