Admonishment / Civil Penalty from a Store

My question involves criminal law for the state of: WASHINGTON state.

So I just got caught shoplifting a $30 t-shirt at Nordstroms today. I haven't shoplifted since I was a kid, I kind of just did it I don't know why. I had no intention of stealing when I went into the store. But it happened, my bad.

I put the shirt on in the fitting room (it didn't have a tag), decided to put my normal clothes over it, then bought another shirt. I got busted by the LP guys as I left the store. They cuffed me and walked me through the store to their office. They videotaped the whole time I as in the room, made me take the stolen shirt off, told me to admit what I did, then sign a bunch of stuff. They decided to do civil charge, no police were involved, it was "admonished" and I have to call their Civil Claims department in the next week and "discuss the civil restitution process".

I'll admit I did it and was stupid. I'm incredibly embarrased and ashamed that I got caught. I'm a college student on the presidents list. And as a progressive guy, I can't really hate on the fact that they decided to bust a normal looking white guy. I totally had the money for it.

My questions:
....Anyone have any experience with this "admonished" civil claim thing for shoplifting? How much I'll have to pay? How long the process will be.

...How did they catch me? The LPs didn't tell me. But I was in the fitting rooms. I hadn't intended to steal until I went in there so I don't think my behavior was very suspicious. I even bought something. I guess I underestimate them.

...What would you have done in this situation, if you were me, and you had shoplifted? Did I do the right thing by admitting, not getting the police involved, etc.?

You would have to ask them how they caught you. They're not likely to tell you, but they're the ones who know.

If you are apologetic, the police aren't called, and you get away with nothing more than a stern warning and a civil demand, you should consider yourself very lucky.