I dropped my iPhone 4S in water?

I was washing my hands and the sink had heaps of water in it, so I grabbed my iPhone to take a picture of it, and I dropped it in the sink. It was in for a good second, and as I grabbed it I dropped it in again but quickly got it out. I grabbed a towel and covered the whole iPhone with the towel. I shook it and some water came out the headphone jack. Now when I use it there's a fairly noticeable, slightly brighter spot on the bottom left part of the screen when I use it. I've already badly cracked the bottom right of the phone and screen, so I think the water must of gone through there. It's my birthday in about a week so I might get enough money to replace/ refurbish it. I can't tell my parents because they already think I'm irresponsible for cracking the screen. I know telling them is inevitable. Anyways, what I need to know is:

a) What's happened to my phone?
b) How much will it cost to fix?
and
c) How can I make sure my parents don't find out

BTW, the camera/ antenea/ mic/ speaker all work fine. I haven't charged it yet (It's on 47% now). And a while ago I dropped it and the screen when white with pink lines running through it, and I thought it was it for my phone but then it switched off and then I manually switched it back on and it was working fine. The next day it goes white/pink again and switches on then off. After everything I've done to it, I don't think I really deserve a phone. Also, I was playing with restrictions and turned Siri off, then I turned it back on, the next day (today) Siri doesn't work, it just goes Voice Control.

Take the back off, put it in a container of dry rice- instant works best. It absorbs all the moisture & your phone should work after leaving it in there for a few hours

I accidentally dropped my husbands iphone and the back cracked, I took it to apple to be repaired and was told the back costs $28 to fix but if I had broken the front the cost is about $300 to fix. They also told me that if I had broken the front because that is where all the touch screen controls are it could be damaged beyond repair.

When you dropped it in water you should not have left it on. You should have turned it off immediately and opened it up and put it in a bed of rise to dry it out. You didn't so the water did further damage.

You are better off getting a new phone as what you describe sounds like there's major internal damage.