Alex Karev has left Grey's Anatomy - and it was just as heartbreaking as fans expected.

In January, Justin Chambers announced he would be leaving the long-running medical drama after 15 years - with his final episode having aired already. And in Thursday night's episode, Grey's fans found out why Alex left Grey Sloan, as well as his loved ones, behind. Spoilers for the latest episode of Grey's Anatomy lie beyond this point.  The episode began with four different letters sent out to Jo, Meredith, Bailey and Webber, in which Alex tried to tell them why he had left Seattle. It turns, he left for Kansas to be with his ex-wife Izzie Stevens - and their five-year-old twins. Yes, Alex Karev is a dad. Alex thanked Meredith for everything she had done for him, as he explained that he had reached out Izzie for a letter of support during Meredith's insurance fraud trial - but also to "hear her voice". "The thing is, I can’t come back. I can’t face you. I deserve the guilt and to be called an ass. I don’t want to be set straight. I don’t want you to say the right thing. Because the one perfect thing isn’t in Seattle. Not anymore. I swear it’s not about you or work or Jo, it’s about me. I left and I’m with Izzie," he said. “She said, ‘Yeah I have kids. Twins.’ It turns out they’re my kids, Mer. Izzie and my kids.” He asked her not to hate him, before asking her to visit one day - but to meet the kids, rather than to bring him home. In his letter to Jo, Alex admitted that she deserved "more than a letter" and that "this right here, this cowardness, it’s officially the worst thing I’ve ever done." "It’s about me, it’s not about you. You deserve so much better than this. I love you, Jo. I love that you are brilliant and brave and no matter what you go through you never let it hold you back. It makes you stronger, kinder. You made me kinder. You love me for exactly for who I was and I loved you. I love you. Maybe it’s not fair to say that but it’s true. But this is also true. I’m in love with Izzie," he wrote. “I imagined this whole life for her where she was happy and had a bunch of kids. I never imagined me in that picture but suddenly I am … There was a part of me that always wondered, always wanted to know, always felt like we left thing unresolved … I reached out to her and we started talking and it scared the crap out of me.” He told Jo that he had reached out to Izzie while getting the letters for Mer's trial, he had found out about their children - and that that was why he was staying. “She’s here in Kansas on a farm in this incredible place in the middle of nowhere,” he said. “Izzie had my kids and I know you get what that really means. You of all people know why I can’t just leave now. I have a chance to make this family whole. I need to give these kids the family you and I never had.” He explained that while he wished "getting everything I always wanted didn’t have to hurt you in the process," he wouldn't be coming home. “But I can’t lie to you and I can’t come home. I’m not coming home, Jo. I can’t face you.  I can’t look you in the eye because I wouldn’t be able to walk away … Thank you for taking care of me when I needed it," he continued, before telling her that he had signed the divorce papers and left her the share of Grey Sloan Memorial. The episode also included flashbacks of Alex's time in Grey Sloan Memorial over the last few years.