Yeah unfortunately this happened to me. After staying single all life, I was talking to this girl for 1.5 years and we talked everyday from 10min-1hr. I just assumed she was single and one day she told me she has boyfriend. I spent 1.5 years dreaming about life together, singing in bathroom and crying tears of joy in bed because she was most perfect and compatible to me and we connected very well. And I'm a guy who believes a person can only love one person truly. So it's impossible for me to love another girl again. Yeah it's that devastating to me.

How do I cope ? I just bury myself in other things. Friends, family, work, hobbies. Sometimes I get on brink of crying but I force to forget it. I regret not confessing earlier. I just thought taking things slow would be better. Take this lesson, guys. Just tell her.

Advice to OP, find another girl.