How Mental Illness Can Wreck a Marriage and a Divorce

Is failure to disclose a significant personality disorder considered a mekach ta’us in marriage?
Are there halachos guiding how to treat one’s spouse during divorce, especially in high-conflict cases?
When is it appropriate to turn to secular courts during divorce proceedings – for example, to obtain a restraining order against a spouse?
Can refusal to go to the mikveh be considered a halachic violation when used as a tool in marital conflict?