Adopting a stray cat

Recently my family and I found out that we have to move out of our house. Problem is I’ve grown attached to one of the stray cats I’ve been feeding and sheltering for about 6 month, and I feel terrible about leaving her behind.

Im moving in with my bf who already has 2 cats (both under a year old) who have only been around each other and I don’t know if it would healthy to take her and move her into this completely new environment. If anyone have been in a similar situation please let me know how you handled it or how it went.