I met someone online and before we met in person I got sucked into talking about sex. I should have had more control over my tongue. My questions are: Should I stop talking to this person? I am ready to confess and repent and ask God for forgiveness. Should I do it by myself or have someone with me to pray? If so who should I have with me?
Clearly if a person quickly directs a conversation toward sex, this is not a moral person and not someone you would want in your life. Heed the warning signs and dump him because the chances are that in person it won't be just talk.
Having someone pray with you is not an absolute requirement, but it is helpful. "Confess your trespasses to one another, and pray for one another, that you may be healed. The effective, fervent prayer of a righteous man avails much" (James 5:16). Who you ask is up to you, but it should be someone you trust will keep you problems a secret and someone you believe is a righteous person.