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You bought the property but she gave you $100,000. If she did this as a gift then she should have reported that on form 709 because that was above the annual limit for gifts in 2008 ($12000 to each of you).
If she gave you the $100,000 as rent prepaid then you would have reported that on Schedule E as rental.
The lawsuit for eviction would be a business expense had you reported as rental. If you did not report the $100k as rental then this is all personal and not deductible.
You are allowed to claim expenses (especially legal fees) against business or against taxable income.
The IRS would see this all as personal and not deductible.
I wish I could advise differently but personal items of this nature are not deductible.