Thinking about the answers to these types of questions is what I truly hate about having AS. Why? Because it's downright depressing.
If I were to answer based on the OP's definition, then the answer is maybe 2. I am not counting family members or their friends, or neighbors and coworkers, because they are not my friends in the traditional sense...they just happen to live or work with or near me, or be related to me, or know someone who is. (Maybe I am overthinking this?)
Anyway, people behave so randomly and inexplicably IMO sometimes that really do not know who would "come looking for me demanding to know what gives" if I unfriended them. I said 2, but maybe it's actually 0. Maybe 10. Hard to predict, just like people themselves! 
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"Be less curious about people and more curious about ideas." Marie Curie
ASD: Officially diagnosed.