Carola seems to have it, it sounds very dramatic about declaring herself "different" - now we are a bit older, there are a few of DH's friends who are well into their 40s, childfree and showing no interest in having DCs, but were still polite about members of our family. They would discreetly arrange childfree stuff, like if we invited them for dinner they would suggest arrivig around 7:30-8ish, clearly after DCs were in bed, or meet DH for lunch near his office one day - so not with family. Would ask about the DCs in the same way they would ask about DH's job, holiday plans and the say DH would ask them about their hobbies and what's going on in their lives...
Your right, it sounds like issues - not just not wanting DCs but being a bit agressive about it all.
If she can't deal with other people making different life choices without being rude about those life choices, then she's not going to be worth keeping in touch with. If you are one of hte first to have DCs, then prehaps it'll take her a while to get used to the fact that her 'no children' rule will make her the outsider amongst her contempories through their 30s/40s and she'll have to make allowances until you start hitting 50s and DCs have all left home again and lives go back to being "the same".
In the medium term, I'd tell her you aren't going to accept her being rude to someone you love, your child is a real person, not a thing - in the same way she probably would get upset if you sat onthe phone slating her DH. Say you don't expect her to love your DCs likeyou do, or want one, but you don't see the friendship lasting if she can't be polite, again as you wouldn't see your friendship lasting if you weren't polite to her DH/parents/siblings etc. when you saw them.
Then if possible, arrange meet up for dinner/drinks without DC, but make it clear you can't just stop being a mum and this is a big part of your life from now on.