I actually started riding more after I had my first kid, because I had less time to do stuff so I merged exercise and commuting together, and it's a good way to clear your head, get some fresh air, etc. It's easy to stay trapped at home with newborns. You realize how precious your time is. I spend less time now on the couch and computer. Take turns with your s.o. or whatever to do something other than childcare/work/chores every day, even if it's just 15 minutes.
The first 6-12 months after a kid is born is tough. Soon after that you can get out on your bike with one of them, thus multi-tasking again.
Last year my kids turned 1 and 4, and I rode 7000+ miles, riding I'd guess on at least 320 days in the year. My wife is possibly more generous with my cycling than some though.
Your co-worker sounds like a d*ck.
My wife is supportive as well........she commutes by bike about 60% of the time, me very close to 100%.
Also.....4 kiddos........age to start, greatly influenced by mother.....
1st-15 months, bike paths only
2nd-10.5 months in the TRAILER, w/ helmet but no additional neck support.
3rd-6.5 months w/ the padded neck/head support from Chariot or Bob.......probably Burley has one, too.
4th-4.5 months w/ head/neck support
All of them did just fine and LOVED the bike trailer. We were just more comfortable with increasing experience. Also, the neck braces help and so does having the infant trained up in a more uprightish jogging type stroller rather than a typical newborn/infant stroller. They build strength and get practice.