Military guy married with kid. Served CS papers from a girl from 3 years ago.

I'm in the military. Was stationed in cali 3 years ago. While I was there I met a local girl. She told me she was on BC, I was being dumb and drinking at the time. We didn't even date, just hooked up a few times. I remember we hung out for a couple days and I mentioned I hadn't noticed her take any BC pills. She turned around and exploded on me and acted very awkward after. I remember realizing then she was lying about the BC. We went our separate ways. I didn't hear from her again. In that time I got back with my ex from my home town. We had a long distance relationship for several months and I flew her out to see me. I went back home and asked her folks for permission to ask her to marry me. Everything went good and we got engaged and are now married in a new home with a hefty mortgage and a new car payment as well with a son of our own. The other day before leaving for work I open up a letter that said child support services on it. It's from this girl back in cali. I am stationed on the other side of the US now. She waited a couple years to do this I'm assuming so that the court will now view her as bonded to the child and be far less likely to award me custody. First thing I'm going to do obviously is ask for a paternity test. However, I need to consult with a California lawyer being as he/she will be familiar with California laws. It will be difficult coordinating everything from the other side of the US and I don't have a ton of money for plane tickets for when I have to show up for court etc. Because I'm so far away one of us is probably going to end up with full custody. There can't really be a 50/50 here. In California law as far as I've read it doesn't factor in any expenses of the person paying child support. Meaning even though I had no idea this was coming my mortgage/car payment will not be a factor. So does this mean me and my wife and son will have to file bankruptcy and possibly lose my home and or car I need to go to work in because I will not be able to afford it if I'm giving her half of my paycheck because the mother works a min. wage job? My wife is a stay at home mom with a BA in early childhood development. I believe I will have a strong case for custody but how likely can I really be as a Father to get custody of my (possibly) kid after she has been with the mother for 2+ years and I've never even seen her? Am I REALLY just out of luck and me and my entire family are going to have our lives turned upside down by this girl if it does turn out to be my kid? I'm sure I can provide a better environment for my daughter than she can but will the court rule in her favor just because of having spent 2 years and bonding to the mother? Anyone with advice or any similar exp chiming in would be greatly appreciated.