ex joined band

so me and my friend are in a band, i drum in it and its really fun we had our first in person meetup today. One of the guys couldn't make it though, so we had to text him the information about what we did. I already am skeptical about this guy in the band, I personally have never seen him with his instrument. Anyways, after practice we text him and he responds asking if my ex who is a total mess and everyone knows i despise can join. i was already asked this a week before, and i said i wasn't sure but i guess because they'll be doing "media" for the band so i thought they likely wont be at most of the practices. They are literally the defintion of my stalker, and i just feel weird around them and they keep trying to get closer to me when i block and ignored them on all platforms and they join EVERY SINGLE THING ive ever done at school. They just genuinelly ruin the atmosphere for me, because i have been told by past friends that they constantly talk shit about me, and even got me suspended from school once for hate speech. I genuinely dont know what to do because ive kicked them out of my life multiple times, but i dont really care as long as they dont talk to me and i warned my friends about it. if they try to get closer, what should i do? i really dont want them to be able to contact me anymore, we are only added in a groupchat where i had to unblock them. They keep snaking their way back into my life, ive even requested teachers if i could sit at opposite sides of the room or even switch classes because i cant even sit next to them or hear that voice. Im thinking about getting a restraining order, because i feel at this point the obsession is insane. should i get one