I have also read your other threads and honestly your issues sound rather severe. This entire relationship sounds toxic and whilst he does have his issues, you also are seriously hard work.
I can completely understand why his family would not want you around if you have created drama in the past, and the fact you keep referring to them as "yes man" people is dreadful. This sort of attitude is probably another reason they do not want you around. They are entitled to a holiday without no drama.
You also need to understand this holiday was booked as a family break whilst you two had ended your relationship, and considering his family is paying and it's their place, they are well within their right to decide they would prefer you not coming along.
You do not live together, so you are capable of coping without him and during your time apart you also managed.
The issues with your relationship run deep, but you will not be in a healthy relationship until you step back and begin to work on and address the problems you have. It is not healthy for your daughter to be raised in a toxic environment.
Please go back to your GP and focus on finding a better route and plan to manage your mental health issues. Focus on becoming stronger and healthier mentally as an individual.
Let them go on their holiday, they are allowed to and this decision was made during a break up. Partners are allowed to spend time with their family, you have been given chances in the past and they were ruined. So you do need to understand that whilst they may be okay with you, it does not mean they're ready to go on holiday with you again.
Take these 2 weeks to go back to the GP and focus on yourself, you cannot continue to live this way, you are affecting your quality of life. There is help out there for you, take the necessary steps for yourself to start a new chapter to a healthier, happier you. Once you are in a better position, you can then work on your relationship.