This will likely be important information that your insurance would like to know about, also if the fire was caused by negligence on the owner's part (hopefully not) you could face a lawsuit especially because someone was seriously injured.

The tenant can't repair at the landlord's expense if the condition was caused by a deliberate or negligent act or omission of the tenant, his or her family, or persons on the premises with the tenant's permission. 

@Craig Stasnbury Here is a saying - please pass it on.Of course nothing I can say or do will fill the hole now in your life.But perhaps this quote, from a Church of England cleric, may give you some comfort.Death is nothing at all.I have slipped away into the next room.I am I, and you are you.Whatever we were to each other, that we are still.Call me by my old familiar name, speak to me in the easy way which you always used.Put no difference in your tone, wear no forced air of solemnity or sorrow.Laugh as we always laughed, at the little jokes we enjoyed together.Pray, smile, think of me, pray for me.Let my name be the household word that it always was.Let it be spoken without effect, without trace of shadow on it.Life means all that it ever meant, it is the same as it ever was, there is an unbroken conti­nuity.What is death but a negligible accident?

It should also state Tenant is responsible for any damages caused by negligence or abuse. 

A residential tenant is rarely responsible for damages to structural or systems except for cases gross negligence by the tenant, nor will the common renters insurance pay for those damages. 

Any increase in marketing costs would be pretty negligible.

I would recommend putting a clause in your lease that the tenant is liable for damages that arise out of negligence.

Making willful or negligent misstatements on your tax return is fraud that can result in stiff penalties.

Your home owners insurance policy covers you for just about any possible form of liability with the exception of negligence.

When it happens, there is usually negligence on the part of the landlord.To answer your questions, your private lender is safe.