I am sorry you had to hear that info, but is it possible she lied to you (about causing it) because she is angry about the impending divorce?
The only thing you can do to feel better is seek counseling to help you handle your anger, grief, frustration - whatever this news has made you feel. You cannot change what happened, and she did not commit a crime (at least the law would not consider it a crime after 7 years - statute of limitations) and her purposeful activity would be nearly impossible to prove anyway, even if you had suspected it at the time.
I am atheist and miscarried 15 months ago and have not been able to conceive since - my husband and I are dealing with medical issues we never knew I had until the mc - the pain lessens everyday - but sometimes it hurts worse when I see babies the age ours would be now. After 7 years in your case, if the pain still seems fresh, please see a therapist - you need to be able to move on for your own peace of mind.