How do I start to cope?

ADVICE AND HELP NEEDED! So, I was in a relationship with my ex-boyfriend for 4 years. We just moved in together this past April. We lived together for 3 months….3 MONTHS and by the third month, I was already staying at my parent’s and hadn’t gone back to the apartment in weeks. Fast forward to literally a week ago, both he and I received a letter that was placed on our door from the Constable. The envelope was addressed to both of us. Well, HE received the letter and proceeded not to tell me since I wasn't staying at the apartment. I knew nothing. He said nothing. THANK GOD another copy of the letter was mailed to us and the only ONLY reason I ever saw the letter was because I get notifications/pictures of mail being delivered to me daily. We received the letter because he didn’t pay rent for two months and said NOTHING. Had I not received a notification about that envelope being delivered, I would have never known. I could have been evicted and I wouldn't even know it was happening. That was my last *** straw. I called the landlord and explained the situation to him, and he said he would release us from the lease if we were moved out by the end of the month (September) aka we had to move out within a week. SOOOO STRESSFUL! I kinda had already broken up with him before this but this like sealed the deal I think for both of us. I was able to move back to my parents and he didn't have anywhere to go. Not my *** problem anymore. He did end up paying the two months worth of rent that he owed. Still a piece of ***. Anyway, we were officially broken up, he moved his stuff out, and I moved my stuff out. To try to make this a “short” story- I found out/figured it out/confirmed two days ago that he is a *** heroin addict. I dated a HEROIN ADDICT for 4 *** years and I did not know I swear on my grandmother's grave, I did not know. I mean well, I knew but I didn't KNOW. There were signs of some type of addiction/deceit/sketchiness that increased over the years but never EVER did I think it was heroin. I guess I respected him too much and thought of him as so much better than that. He kept a heroin addiction from me for 4. ***. Years. Am I that *** dumb? How did I not know? All…I mean ALL of the signs were there. Did I just not want to see them? I feel so many *** emotions and it’s honestly a lot to handle on my own right now. I was betrayed. Lied to. Stolen from. Probably cheated on. Taken advantage of. Blamed for everything. By someone who told me he loved me and I believed it. I feel *** violated to tell you the truth. Damaged. Used. How do I start to cope with this? Where the *** do I even begin? How do I learn to trust again? I don’t trust my own shadow now. All I’ve done is cry. I can’t stop crying. Maybe/hopefully you have read this far and have any advice/support/anything to help me start to accept, heal, and move on because I don’t know how to do it on my own.