Girlfriend broke up with me after 10yrs, cause she is unsure and never dated anyone else. Should i pursue her?

We have been together for 10 yrs straight through highschool and i even moved countries to be with her after highschool. we are know 25 and 24 and have been so in love with each other. we are the happiest and closest couple we both know and most of our friends are single.

she freaked out when she found out that i bought an engagement ring, and she is saying that she needs to find out if the level of happiness is the happiest she will ever be, she needs to know who she is. this is what she is saying to me.

she wrote me a letter saying that she is sorry to do this, but she needs to do this as she needs to find out.
this was 3 weeks ago and she has completely blocked me out of her life she didnt respond to my emails, txt, calls. so i gave up trying to contact her.

i havent spoken to her in over 2 weeks, the longest we have given each other space. i dont know what to do, i am going to write a letter to her explaining how i feel as she blocked me out completely i do not know what to do.

some of her friends are saying that she is just confused and needs to figure stuff out for her self. she works in advertising and is studying her masters so she barely has time to think and relax let alone think about herself.

should i just give up? i dont know. i love her so much but i cant take her back as soon as she gets with someone else.

we have a strong history of taking it slow with each other and the thought of taking her back after she has been with someone else drives me insane.

i have heard from other people that she is doing fine, which i cant understand. The last 3 weeks of my life have been the worst in my life and i cant see a future without her.

Anyone have any similar situations or any advice?

Thanks so much.