This seems more like a family or criminal law issue for which you may want to consult with a family or criminal law attorney. Alternatively, you can always contact the police if the harassment has you fearful for your health and safety.
An employer cannot discriminate against an employee due to their pregnancy. If any action taken is motivated by the employee's pregnancy, then the employer may be opening itself up to liability. If the employee is requesting light duty, and cannot perform the essential functions of their job with or without an accommodation, however, then the employer may be able to terminate the employee. It is very fact sensitive, however, and any employer should consult with and work with an experienced...
The eavesdropping itself may not be actionable, but if you think that your boss was threatening you due to your union activity, then you may have a claim on that aspect of your facts. You should speak to an employment/labor attorney more specifically regarding the facts and circumstances if you believe that to be the case.
If you believe that there was a discriminatory motive to the harassment to which you were subjected, then you may have a claim. In that situation, you should contact an experienced employment attorney to discuss your facts and circumstances in more detail.
You do not have to send your rebuttal to your former employer. You can just send it directly to the SDHR. Additionally, it may be wise to review your matter with an employment attorney as they may be able to assist you through the SDHR process and it is always wise to have an attorney for these types of matters.
As a probationary employee, they generally can terminate you, but if you think that the actions are being taken against you based on false allegations or that you are not being afforded an opportunity to explain any of the issues due to a discriminatory motive, then you should contact an employment attorney to discuss the details and facts of your case in further detail.
An employer is entitled to deny unemployment, but if you think they are doing it in retaliation for your filing a complaint, you may be able to use that as evidence of their unlawful conduct. You may want to contact an employment attorney to discuss this with them and provide some more facts regarding the situation.