OP asks, if selling 3% share of a company would "harm the company."
If this is a private stock buyback by OP's company, the company is spending cash to buy OP's shares. Simultaneously, the company is increasing its own shares by an equal amount. So the company balance sheet is not harmed. Consider, however, the impact on the company's cash position. The company may need to raise 1.8 million in cash to buy OP out, if it doesn't have that cash already.
If this were a publicly traded company, given a market capitalization of approximately 60 million dollars, such a sell could be well in excess of the average daily traded volume of the stock. The broker might be unable to fill the whole sell order at the current price, all at once. The market price may decline. A declining market price does not harm the company in the long term, and in fact may represent a buying opportunity for other potential investors. The market price will eventually correct itself.
However, from OP perspective in the above scenario, reducing the market price of company shares would affect the immediate value of shares held by other company shareholders... some of which OP may care about. To avoid impacting those other shareholders, OP may consider a more gradual reduction of their shares to zero.
If this is a private transaction between OP and another private investor, then the company isn't financially risking anything and the terms of the deal are private.