Help! how do I deal with passive aggression?

Hi ladies I need your advice. Sorry it's a long one but necessary to give you a picture of what's going on.

My husbands best friends wife constantly makes me feel like crap after every catch up we have together.

In a course of conversation she will talk about the things we've been getting up to says a quick positive about it then proceeds to find any negative there possibly could be. She saids things in a very calculating passive way to try and not reveal herself as aggressive or confronting with her negative comments.

She constantly makes comparisons between what we do or have done consistently, always trying to convey that she is better than us. For a long time I never realised exactly what was going on, I knew something was up but could never put my finger on it. Then it dawned on me one catch up when she said that my husband and I should stop being in competition with them. She said it in the most calmest of manners almost laughable but she meant it.

And since then I see exactly the malicious context behind what she saids to me and about us in front of our group of friends. An example she always loves to mention is that I'm sooooo competitive she'll say this in front of anyone that's in ear shot even when it's got nothing to do with a subject we are talking about. It's interesting to me because I wouldn't say that I'm in competition with anyone I'd say ambitious if anything.
I would describe my husband and I as go getters, we have an idea and we do our best to go after it. We've always been about the things we want to do and get out of life our own personal journey, but because some of our goals are the same as theirs it's apparently a competition. And by goals we are actually talking about the ones pretty much most people have marriage, kids, own home, travel etc sounds familiar.

When she visits our home she feels perfectly comfortable going through any papers we've left on our kitchen bench could be a statement or letter anything she'll pick up and take a good look. It's like we are constantly under surveillance even to the point of the outfits I wear or the hair cut I have. On Facebook she comments on nearly everything I put up there pretty well straight away, it's that noticeable my brother even mentioned it to me and that's saying something cause he's barely on there.

In the context of talking about herself she always refers to any negative in her life and how the world is always against her. She always perceives herself as being so hard done by with everything and anything. And her story always is worse than yours even though you've gone through the same thing it's always "oh at least you had this..... I've never had that" and comments to that nature.

To date I've been mostly avoiding her just saying to my husband that he can go catch up with his bestie. But more often it's been group catch ups and I do my best to keep away and talk to the others. I usually sit at the opposite end of the table but find she'll come pull a chair up beside me and fire off questions at me like I'm under cross examination.
I'm always friendly and i happily answer questions I have no secrets. But I've caught myself at times stooping to her level in retaliation for a hurtful comment she's said to us. And that's not who I am I'm not a vindictive person I always praise for achievements and give comfort in the hard times.
How do I deal with her? It's my husbands best mate and I don't want to have this cause a problem between them, they've been friends since they were 5. And all I want to do is be friends and enjoy catch ups and have a good time but she makes it impossible. Please help!