[Carrier] iphone 5 verizon on international use

hello everyone, lets see if someone can answer my question... i havent really seen a straight answer online but here it goes.

i have a iphone 5 currently on a plan with verizion.... i plan to travel to costa rica for a 1 year and use my phone over there.. I am aware that my phone is GSM unlocked internationally and that i can use it in costa rica..

thing is that since i am still under a plan... i dont want my line to go to waste so i plan on activating another line and give it to my daughter... i spoke with the verizon rep she told me that if I activated my US line with another phone my phone will be "blacklisted" i am assuming she meant Bad ESN

so my question is.... i dont care if my phone cant be activated in verizion anymore.... will it still work on my Costa rica GSM line??

untimately i would just sell it un costa rica and buy my self a new phone when i get back to the US

thanks in advance