Why are you asking if it is OK to feel what you are feeling?
Emotions are very personal things. Trying to deny or suppress how you feel is harmful to you and to your relationships. You should allow yourself to feel whatever you feel. Feelings are neither good nor bad of themselves, only the actions that result from those feelings.
So they say.
Several thoughts go through my mind. The first is, "What people say and think are not always the same", and each person will handle breakups differently. Strange as it seems, if I think about the women in my life, I can think of many influences each has had on me. Most of these are very positive, few are negative, and I have had a few bad relationships. To say, "I haven't noticed that you are not in my life" sounds like denial and is being a bit immature.
You don't know that for sure, we have no idea really what may be going on in other peoples heads or lives.
I think what's happened is , you say it's an ex friend, but it clearly isn't. If it was an ex friend, you wouldn't care what they thought or said or did. But you clearly do. Which means, you do still care about them.
How did they become an ex friend? Was it a mutual thing or was it one of you losing your temper and saying forget it and secretly hoping they would run back - just a rhetorical question.
I think if it does bother you so much, which I see it does, you need to get in contact with them and make things right. Life is too short to not talk to someone who you clearly still care about
yes its ok to be upset
Don't feel this way just because of others