Relationship with boss, FMLA pregnancy leave, retaliation?

I had a relationship with my boss, and became pregnant. He told me he was in the midst of a divorce. In August, he went on FMLA leave after finding out he had testicular cancer that spread. In late September, he told his wife that I was pregnant with his child. She called me on my work phone as well as my work cell phone and harassed me constantly, leaving messages threatening me at work and at home. She also called my employer and told them what had occurred (with false information). At that time, I was put on bedrest and went on FMLA leave. I gave birth in late October. At the beginning of November, my boss/child's father passed away. In late November, I applied for Social Security survivor benefits for my son, and his wife already had the benefits for her two children. They advised her that her benefits would be reduced after I got a DNA test with my son's aunt to prove my boss was indeed his father. I returned to work in mid-December. The wife recently called my employer again complaining about my filing for SS benefits, and claimed that I have been harassing her (not true) and that I misused my HR position at work to get the information needed for the SS benefits (again, not true). Because of that phone call, the co-parent of HR called me and advised me that if one more complaint arised from this woman, I would be fired. Since returning from leave, I have not been treated the same as I was prior. I was advised to step down from my position because now having a child prevents me from working overtime. My employer has threatened to cancel mine & my sons health insurance claiming that payments were not made while on leave and they were. I have proof as the checks were cashed. They are constantly speaking with my son's fathers wife. I am the employee, and not once did anyone ever ask me if her claims are true. They assumed they were, and called me with threats. When I ask them to stop talking to her, they blow me off. When I stated that SHE is harassing ME, I was told my personal business is just that - my personal business - and should stay that way....yet they delve into my personal life everytime this woman calls with her bogus complaints. This woman is doing everything she can to retaliate against me, and I feel as though my employer is now doing the same. Do I have a case if they fire me?