public boolean modifyFriend(String emailModifying, String emailModified) {
		
		PreparedStatement ps;
		String statement;
		
		//only modify any of emailModified's relationships if there
		// is mutual friendship. In that case, severe the tie from emailModified
		// to emailModifying (this is the remove friend case when both are already friends)
		if(isFriend(emailModifying, emailModified) &&
				isFriend(emailModified, emailModifying)) {
			statement = "DELETE FROM " + Constants.FRIENDS_TABLE + " WHERE email1=? AND email2=?;";
			
			try{
				ps = conn.prepareStatement(statement);
				ps.setString(1, emailModified);
				ps.setString(2, emailModifying);
				ps.executeUpdate();
				ps.close();
			} catch(SQLException e){
				e.printStackTrace();
				return false;
			}
		}

		
		//if emailModifying is already friends (or is pending to) with
		// emailModified, remove that relationship
		if(isFriend(emailModifying, emailModified)) {
			statement = "DELETE FROM " + Constants.FRIENDS_TABLE + " WHERE email1=? AND email2=?;";
		}
		
		//otherwise, add that relationship
		else {
			statement = "INSERT INTO " + Constants.FRIENDS_TABLE + " (email1, email2) VALUES (?, ?);";
		}
		
		try{
			ps = conn.prepareStatement(statement);
			ps.setString(1, emailModifying);
			ps.setString(2, emailModified);
			ps.executeUpdate();
			ps.close();
		} catch(SQLException e){
			e.printStackTrace();
			return false;
		}
		
		return true;

	}