The scary "L" word

So.. I've been with my boyfriend for about a year and a half now. We are just perfect together and always laughing and enjoy being together. Here lately I have been having bad feelings; anxiety, frustration, low self esteem, etc. He's the only one I can talk to about it for support and encouragement. I was asking him why he even sticks by my side and he listed several reasons and then turned it on himself and listed his imperfections and asked why was still with him. My response wasn't hard to say but afterwords it was awful. I told him I loved him for the first time.. After I said it, the anxiety set in as I waited for his response. I was scared what he was going to say. All he said was he wasn't ready to say it back.. He said he wasn't going to tell me what I wanted to hear because he wasn't ready for it. Wasn't ready for the commitment it brought or whatever. I could tell he was pained. I could see it on his face. I was feeling awful and burst into tears. More reason to tell myself I'm not good enough or I'm not what he wants or there's someone else.. He keeps telling me he "likes me a lot" and that he doesn't want us to separate but he thinks I need space after all this.. I am clueless as to what to do. I mean.. Do I leave? Do I apologize? Do I stay with him and wait for him to love me back?? I mean.. That just doesn't sound right. It sounds awful and I'm torn and heartbroken and depressed over the matter. Things are a little awkward between us and our tones. Did I fuck everything up? Are my feelings for him wrong or too soon? What do I do...? Any advice would be greatly appreciated. I just want this agony to stop.. Thank you for taking time to read through my situation.