Walmart is aggressive in prosecuting theft, so you can expect to be charged. Yes, you need a lawyer. S/he can negotiate the best resolution of your case. The best you can hope for is NJ's pretrial intervention program for 1st time offenders. If you do what is required you can avoid having a criminal conviction record. I can't predict whether you will have to post a bond, or whether you'll simply be given a notice to appear in court. Your lawyer can walk you through the procedural steps in your jurisdiction.
And keep this in mind: There is absolutely nothing in Walmart, or any other store, that is worth ruining your life over. Criminal convictions will destroy many many paths and opportunities in life that you might otherwise pursue.

