Every time my wife runs into an old friend she has the habit of kissing them on the cheek to say "hello". It drives me nuts! I tried bringing it up once before and she got all defensive and insulted because she thought I was accusing her of being a slut. Then she said I was making too big a deal out of it. Sometimes I wonder if these "old friends" are men she slept with, but if I ask that there will be a huge argument. How can I get her to stop kissing old friends (male or female) and explain to her that it's wrong and that it angers me?

It doesn't sound like she's has much consideration for your feelings.  If she did, I'd think she'd at least try to be cool about it, even if she thought you were nuts.   Sounds like she's kind of in your face about it.  That makes me think you are letting your wife take advantage of you.  Maybe you're "too nice" to her.  I don't know what The Traditional Catholic equivalent is to it, but it sounds to me like you need some kind of assertiveness training.  Oh and if I were in your shoes, I'd probably not take on the kissing thing, since she's already dug her heels in about that.  My guess is there's probably a lot of ways she walks all over you, that you hardly even notice.  So, I'd try to become more attune to that and start sticking up for yourself in ways that are easier to win, until you finally work your way up to the kissing battle.  By then, maybe it won't be such a big deal for her to give into you. Also, I'd take look at your "self esteem."  That's basically about getting what you want and you seem to be having a tough time with that.  

Also, it seems like you gotta teach your wife to control her temper.  That's easy from a Catholic perspective.  Teach her that wrath is a sin, patience is a virtue and it's rooted in humility.  Catholic encyclopedia has some nice definitions you can study and teach to her.  Most people don't equate their bad temper with wrath.  So, you have to teach her that.  It's just part of your marital responsibility.  She'll be doing the same kind of things to your kids, she does to you.