I'm gonna give you the benefit of the doubt due to your relative transparency in this matter despite there being some issues with the information divulged here, likely due to a combination of obscuring personal details and general distress around the situation. Ultimately, Kelly should be the one facing the heat based on everything we can gather, but Fiona is potentially uniquely qualified to show exactly what Kelly was doing or at least give us more leads.
At the end of the day, it's her choice and you shouldn't pressure her into doing anything, but the possibilities at play here are incredibly serious and ignoring them won't make them go away. That's all I wanna stress.