Do ihave to get a lawyer if the other party claim to the fault and have insurance?

I believe you are saying that the other party admits fault and has insurance. Whether or not you retain an attorney is really up to you. One factor may be if there are any injuries for you or your passengers and if so are they real injuries or just bruises. When you obtain an attorney you will be paying someone else 30-50% of you total payment received from the other party. The legal fees are not in excess to damages but come out of your damages. I suggest that you work with your adjuster and see how everything goes. Most adjusters want to handle your claim fairly and get you back to where you were before the accident.