You can be the bigger person and apologize, whether the fault was your or not, if the relationship meant that much to you. You can make the effort to say; “I’m sorry that we ended this on such a bad note. This is how I really feel about…”, and/or; “I miss having you in my life, and hope that someday we can put this behind us, even if the relationship changes from what it was, I still want you to be in my life in one way or another.” Or, if you no longer want that person to be in your life, but feel that there is something unsaid, you could just send the email or a formal letter on paper. It’s tying up a loose end. If you venture nothing, you gain nothing. It is not an indication of weakness, but of maturity. Good luck.