Short answer: Yes, you really do need a lawyer.
Long answer: Yes, you really do need someone who, above anything else, is an expert in the legal field and will do everything in their power to help you and keep your best interests in mind. You really do need someone to review all the evidence the State may or may not have against you and determine whether it was legally obtained. You do need someone to advocate on your behalf to the State prosecutor and court. You do need someone to check the other side and, if anything was obtained illegally, move to suppress that evidence. You do need someone who is a trained professional with years of experience to dig through everything on your case with a fine-tooth comb.
You need someone who can assist in forming your defense, interview witnesses, obtain discovery, assist with drafting legal documents, coordinate with you on the best defense possible and advocate for you at every turn. Your attorney should answer your phone calls and emails when you have questions. They should be a fighter. You need someone who genuinely does care about your case, your life going forward and appreciates the great responsibility they have undertaken when handling your defense. You need someone who takes this just as seriously as you do, or maybe even more seriously.
After all, I would never choose to represent myself if I was accused of a crime, even though I could and would do a good job of it. Abraham Lincoln once quipped that “A man who is his own lawyer has a fool for a client.” That advice still stands to this day and will in perpetuity in American criminal jurisprudence.