Have you heard this saying 'it's history repeating itself that'? I think it is one of those that is bandied about quite a lot, like many things it is easier said than done. One of the hardest aspects of this kind of situation is spotting it and then deciding to do something about it. Can you do something about it?
I think it can be a hard situation because if you say to others 'I need to break the cycle or history will repeat itself', it may make those in that cycle feel defensive, more so if they do not see it like you do. This can prevent people from acting on what they have realised is happening in case they upset the apple cart in the family. So on goes that vicious cycle and most likely it may pass on again and again. Nothing ever changing.
Another one is 'they are a product of their upbringing' or 'you can see why they behave that way, have you seen their parents'. There are many ways people summise other people's lives and behaviours, judging them by the snippets they see. You cannot possibly know what another person has going on or is going through, so it is best to try not to assume things about others. The only person who can truly know if any of these things are the case are the people going through it. The biggest and probably hardest part is realising what is happening and then changing it around for the better. This takes courage and lots of strength.
Breaking that cycle can be done with the right tools, support and understanding. After all your loved ones should want what you feel is best for you without judgment and taking it personally, we all make mistakes and if someone learns from them then that has to be good right?
Do not be afraid of what others will say, if you want to improve your life you must go for it. True friends and family who care for you will only support you and be behind you. Those who do not, family or not may not be always what you need. You do not have to put up with others disregard for you just because you share a bloodline. Talk things through calmly and try to understand each others points of view, remember you do not have to agree with people all of the time to be part of their lives.
Be proud of the good breaking that cycle is doing for you and maybe the generations after you. It is not easy and can be very traumatic depending on the problem, self care is acceptable and it is fine if you take that journey alone. You do what is best for your mental health and wellbeing and your physical health will thank you for it too.