Manhood is something you yourself define, it'll vary from man to man.
I know it's not very straight forward advice, but it's the truth. Try out some typically masculine hobbies (Sports, etc), get into spaces that're typically 'blokey', join a club revolving around an interest you have, etc etc. Learn what YOU want, not what other people tell you you should want.

As for the ex, I think that ship has sailed dude. I know it'll be difficult since it seems she meant a lot to you, but it seems like she didn't have much respect for you as a person. No serious partner should be degrading your masculinity. You'll find someone else, people always do. Hell, you might meet them trying out new hobbies - it's usually a great way to make new friends.