Keep it professional, not personal

In your mind, be clear about your intention: not to shame the colleague who interrupted you or act on a grudge, but simply to make your point complete and clear. That requires focusing on responding over reacting. 

A reaction is instantaneous, like feeling insulted and defensive. A response involves patience and consideration, leading more quickly to corrective action: 

• To keep the focus on insight, not insult, avoid saying things like “Before I was rudely interrupted…” (Believe me, your interrupter will get the message.)
• Don't talk over your interrupter (perhaps louder), as if in a battle to see who backs down first. This tactic creates conflict and competition.