I have documents showing that this individual has shared the paper content with other people
Nothing necessarily wrong with this. It's polite to get permission from co-authors especially before sharing broadly outside your group, and can be rude not to, but it's normal for academics to talk about what they are working on with other academics close to them.
Also, the individual has added co-author to the paper without my consent
If this third person has done work on the paper amounting to authorship, then they must be an author. If not, then they must not. You and your co-author(s) and potential co-authors should come to some agreement on who meets this qualification, but I don't think it's really time to call out an ethical breach or "report" to someone, it's just time for you to have a conversation about authorship with your co-author.
Lastly, think about what you're trying to achieve here. Starting some sort of ethics proceedings against someone you work with is an absolute last resort action. It's unlikely your relationship will escape this action without irreparable damage.