Does he still love his ex?

**Sorry for the long post!**

I met my boyfriend over the summer and we quickly became friends. At the start of fall, he confessed feelings for me and asked me out. I asked him if we could just take it slow and see what happens. Shortly into our courtship, he found out his ex of 5 years had cheated on him while they were together.

Suddenly, he was heartbroken and blaming himself for the demise of their relationship. I quickly backed off and became a friend again, as he seemed to be going through a lot of turmoil.

Eventually he got it in his head that he needed to win her back, despite her cheating on him and continuing to flaunt her new boy toy in front of him. When he couldn't win her back he fell into a depression and started to suffer at work. I stayed his friend and emotional rock throughout all this, which sucked because I really liked him, but he had nobody else he felt comfortable opening up to and I didn't want him to be lonely in that state of mind.

He pulled himself out of his spiral and finally stopped talking about her to me. We continued our friendship, and throughout this ordeal I'd started seeing other people. He seemed really in love with her and I needed to keep my mind off of him, especially when he'd tell me how jealous and angry he was that she was with other people. However, I did still like him and when he brought up the idea of a relationship again later, I was hesitant but really wanted to give it a shot.

We've started dating and it's been a dream, but I can't get the idea of of my head that I was just a consolation prize for when he couldn't get the girl he wanted. He's repeatedly told me he was just blindsided, as she basically been his only family for five years and couldn't believe she's hurt him like that after planning a life and getting a puppy together. He was also afraid of losing someone who was his only tie back to his family (they both came from the same country which is where they'd first met). He said he was just confused, but that he'd liked me before she told him about her cheating, and me choosing to stay by his side as he worked his issues out made him really fall for me. I want to believe him but his ex has become a major insecurity for me, especially because I was the one who he talked to about how much he was pining for her.

Should I trust him when he says he's over her? Or am I just a rebound after being heartbroken by the girl he wanted to spend the rest of his life with? I've never been cheated on so I'm not sure if his reaction was normal or not.