One of my primary preceptors is similar to your preceptor's personality. I also question why such RN's choose to precept as well.
With regards to the micromanagement, I believe this stems from the RN being control freak and likes to be in control of his/her environment. I think the control comes even moreso into play given the fact he/she is ultimately responsible for the patient outcomes as well as training you properly.
Insecurity may play a role with the undermining and poor treatment. I believe a person who is secure with themselves will not put down, belittle, and/or gossip about another individual in such ways, especially a new grad RN.
Do not inherit their problems. Something lead to the individual to become what he/she is today. Your main goal is to get the most you can during this orientation period. Continue to do your best and keep in mind this orientation period will pass. You cannot change your preceptor's personality. However, you have control on how much you'll allow this individual to influence you and your future nursing practice. Learn the good and do away with the bad. Set professional boundaries when needed.
One step I took to address this issue was speaking to the nurse educator directly. Prior to this, I tried communicating some of my thoughts to my preceptor to no avail. While meeting with the educator, I did not point fingers but rather clarify what I'm suppose to learn during my orientation and the steps that should be taken to ensure that I'm getting the most I can while I'm on orientation. The educator communicated the goals directly to my preceptor. After this, things have significantly improved. I'm operating moreso as the primary nurse while my preceptor is assisting me where/when needed (in addition teaching when opportunities arise). I also ensure to maintain open communication with my preceptor by communicating procedures, medication administrations, etc. prior to doing them despite I may know how to do them (just to keep the individual in the loop).
The day usually ends with getting constructive feedback from my preceptor. This has been very beneficial as well. It's not to say all is perfect. However, it has significantly improved than before and I'm learning a lot each day.
The suggestion I want to most emphasize is to not allow this preceptor's negative behaviors get the best of you and/or distract you from your goals. Find ways to work around it. Perhaps, it may involve changing what he/she perceives about you, speaking to a nurse educator/manager, etc.
Finally, maintain your confidence that you'll have that knowledge one day. You may be precepting a new RN in the future. Having this kind of experience under your belt teaches you what not do or say to a new RN who is learning the ropes, already stressed from the typical emotional roller-coaster new grad period.
Best wishes getting through orientation! You're not alone with this!