It would be wise to go and see a business adviser so that you are including objective financial advice in your decision making. However, it is clear that this decision is also an emotional one for you.
The combination of family and business is an intense one and often the structures and conditions of one interfere with the other: for example, sibling rivalry tumbles into business with chaotic results, or the requirement of business to focus on results has catastrophic results on family relations. What might be needed here is a combination of family therapy and business negotiation, and this can often be found in consultancy organisations as this is a familiar story.
Your starting point can be to invite the owners to a conversation about the success of the business. Focusing on what everyone wants allows for at least one point of agreement. Then, before going any further, you can outline your concerns for the future of the company, and you will need to do this honestly.