I certainly think that there is more to this story than you are letting on. However, to answer your questions. If you continue to ignore the police you could face charges for "accessory after the fact" sometimes referred to as obstruciton of justice. Thats only if you know who committed the crime and continue to conceal it. If you knew that someone planned to commit a crime and in anyway helped in the commission of that crime by saying for example, where and when money or other valuables would be located, you could be charged as an accessory before the fact. Either situation is not a good one to be in. My suggestion is to go through your attorney and arrange a meeting with the police and prosecutor. Ask for immunity from prosecution in exchange for your testimony and text messages. The guy who is did this is certainly not doing you any favors.
The police can get a search warrant for your records. Phone companies keep track of calls, etc, for different periods of time. It is not something that takes a long time.