My teacher caused me distress

Hey I am a 19 year old engineer student living in coorg...this is my first vent...so please comply....our college is the only college in the whole district...I wanted to take up a correspondance degree and I chose to stay in a tier 3 college near my home before u judge y I landed up here..I have a mathematics lecturer ....I'm in 3rd sem studying cse under vtu ...but my college is in coorg ...I can't name my college if u want to look up u can search engineering college in coorg and my college will pop up....it's trashy and mediocre... coming to the math faculty...let's call her alexa as I can't name her directly but her name starts from A ....that lady has been ragebaiting me since day 1 of college....and not just her I became a easy target....it got me so stressed that I skipped going to college atleast twice a week....it was very stressful for me to sit in her class coz she would find a reason to taunt me anyday....I don't like attention and drama and I choose to sit in a last bench....hell nahhh....she wants me to sit in front of the class and listen to her and make me feel terrible.....she usually make us write notes in our class and I partially take notes as I don't attend half of the time....but then at the semester end she asks me to submit notes completed or she threatened to cut my assignment marks which is 20% of my mathematics grade.... according to vtu that is unnecessary and I don't budge....she threatened me and also insulted me regarding the same infront of other facilities of the mathematics department... lemme be clear my grades are descent ....I felt very frustrated and I knew any adult would not take me seriously or whatever I say seriously so I chose the option of writing a formal descent complaint on the redressal portal of the college.....in a standard college the redressal portal is managed by the hod and the principal....but our college has a management which handles these stuffs and situation escalated.....it's been a month this happened....tbh redressals should be kept private by both the complaining end and the principal but our college lack professionalism ,they do not protect student privacy and shame students who come forward in these matters and also target students (basically my college is trashy, and facilities are unprofessional as hell)....they made me write an apology letter because I wrote a redressal letter.....are they assholes or did I overreact....whats your opinion