What am i going to do my girlfriends left me?

Im 28 and have just been dumped by my girlfriend of 4 years. She's 23 and i love her dearly, ive tried everything, i even proposed to her because i want her in my life forever. She has made it very clear its over! Im devastated! She said ahe's young and wants to live life and go on adventures..... on her own! I said id wait if she didnt want me with her and she said theres no point coz she doesnt love me anymore! I didnt think you just stop loving people like i dont stop loving my brother or mother, she was like family! She was my first girlfriend ive always been a loser in love until i met her but now she is gone. Most of my mates are married and have/having kids! Im too old to date now arent i? What am i going to do? I love having a girlfriend and have a high drive! Im feeling lonely already! How do i meet someone as beautiful as my ex now! Im going clubbing on the weekend with my single mates! I think i was to attentive to her or is it coz im balding. Wanted to b a young dad!!?