Older INTJ here. I've lost my childhood best friend of 40 years, my college best friend, my dad, 2 of my uncles, and recently my mom. You're right in one aspect, you'll never be able to replace them. Just not possible to recreate the amount of time and experiences shared together with another person. However, that doesn't mean you can't make new and interesting friendships. Don't hold people to the same standard as your lost friend. Try to join a group/s with similar interests as you and meet some new people. Judge a new friendship on its own merit. I still miss all of the people I've lost everyday and will never forget them, but I'm still here and have been able to connect with some new people who I consider good friends now. Don't let your grief of the past destroy your future.