advice please

So I am 22 I've had bad anxiety and depression for years now. I was finally at a good point in my life of dealing with it and these past few months it has been coming back a lot. I just started dating this guy however I've knoewn him for years. I honestly thought he was the one as he's told me I was cuz he's been in love with me forever and I finally gave him a chance and fell for him. He just stopped talking to me out of no where, no explanation, just ignoring me. I'm not one to blow his phone up so all my anxiety and anger is in me. Idk how to stop my anxiety when dealing with a relationship. I can't eat or sleep all I want is an explanation. How do y'all handle anxiety due to a relationship? So you're not taking things out on them blowing their phone up etc and making it worse???