Do not trust me, trust someone who knows:
As an investigator, I can only agree: everything you say can and will be used against you. One of my most respected teachers on the subject taught me an other trick. It comes down to screaming 'I NEED HELP' and I will leave it to the reader to think up the context as in when the time has come to [ab-]use this.
Most people are not even aware that LYING is allowed in the process of interrogation...