I need help please

I fell in love with my ex we never really worked out but with him I felt safe. from falling asleep on the phone, long paragraphs, to our long 10 months together. we broke up and then on and off for a while. i’m in this new relationship but my boyfriend is nothing like my ex. I wish I got the long paragraphs, better conversation, falling asleep on the phone. I don’t know why these feelings don’t go away. I went to my ex’s job and I saw him and my heart started racing and I got super happy and very shy. what do I do? why me?