Is It Illegal For Someone To Release My Personal Information?

hello,

theres more context and a long story attached to this question, but i want to keep it short.

me and my old friends had a very rough falling out this year. i have had them blocked on everything for the past three-ish months and haven’t posted anything publicly about them regarding the falling out. recently, i discovered that these people gained access into my personal instagram somehow. i cannot think of any possible way this could have happened other then i signed into one of their personal devices a long time ago and it saved my password. i got no warnings in my email, on instagram, or through my phone number that someone else logged into my account.

i use instagram as my main source of communication so everything, i mean everything, is on there. the way i found this out is they found chats of me complaining about them to my other friends. they saw things i said about them in my private chats that upset them and are contacting people who know me (cant contact me as i have them blocked) to tell me to stop saying this stuff about them or “it will all be released”. they read/typed personal texts between me and friends (who have confirmed to me didn’t send them any screenshots/recordings/texts) which is enough proof for me to believe they gained access to my personal messages. mentioning things from over three years ago, word for word, that truly has no relevance now.

they are threatening to blackmail me if i continue this behavior over MY PERSONAL TEXTS that they sought out to see. within these texts are extremely personal information about my life, my family, and unfortunately nude pictures of me i exchanged with my partner. they haven’t mentioned releasing these nude pics of me, but based on a lot of these behaviors, i wouldn’t put it past them. i never gave willingly consent to see my personal messages and was unaware of them going through them and recording everything.

my main question is, what do i do about this? they have all of this information they are just sitting on waiting to release it publicly on the internet. i want to send a cease and desist letter first, and i want to go to the police as well. im worried if i go to the police about this though, i wont have enough evidence to give them to form a case. im not even sure what laws they could be potentially breaking doing/threatening this. any advice is helpful thank you for the help.

edit: my instagram account has been deleted i can still gain access to it until the end of january if needed, but its not up anymore