I know what you mean when you talk about feeling obliged to help a family member but that being stressful and counter productive at a certain point in terms of your own health and recovery. It's a really tough situation.
Basically it's the same one I'm in with my own dad. With him, I know he just loves having me around even if I dip into some of his meds (cannabis, and especially his GBP, although he doesn't seem to use much GBP so it's not like I'm keeping him from getting his medication). It's inappropriate I'm taking someone else's medication period, but it would be doubly so if he needed to take every pill himself... Iono I just really don't like taking anyone else's meds considering I used to be a bit of a thief in that regard - I don't want to engage in that kind of behavior and it leads me to feeling like a bit of a piece of shit which just makes me want to use more drug which I definitely don't need as an influence right now. I know he understands and just appreciated having me around considering I'm doing so much better in all regards (especially in terms of ethically questionable choices), but it's still difficult for me considering a lot of the guilt I have surrounding my relationship with him, as well as other/prior difficult aspects to our relationship.
Hopefully you can let your family know you need help in terms of managing relationships with family. Even if you feel strong obligations, perhaps in part due to prior unethical behavior there is some guilt surrounding, your other relatives have obligations to help out with family too. It isn't fair or reasonable for anyone to have expectations along the lines of you having to be there for them all on your own, without a helping hand when you need it.
Have you tried reaching out and talking about some of these issues with anyone? It sounds like your family is generally on the more supportive side of the spectrum, so that is a huge leg up, but it still sounds quite difficult. And understandable, but that doesn't doesn't necessarily make it any easier. But it's super important to communicate our needs and feelings surrounding them clearly to family members. Not in terms of "I don't like that you do X behavior," more so in terms of "when I experience X it makes me feel Y."
I know with my own recovery, I have to be very, very careful with the amount of time I spend around my parents and family. It just causes so much stress - anxiety on everyone's part really defines a lot of my parental and familial relationships. And that's been the dynamic long before drugs ever came into the picture or I started to really struggle. Anxiety can be very hereditary.
I hope you're able to continue to be sensitive to your own needs related to stress and recovery when it comes to dealing with your family. Especially considering it sounds like they would totally understand if you where to explain to them how it's difficult for you. I doubt anyone in your family, especially not you daughter's grandfather, wants to cause you stress even if indirectly. It's easy to feel like I need to have perfect relationships with my family members, especially with the obligations I feel as a son, but that kind of perfectionism is so entirely counter productive.
I'm no good to them if spending time with them causes me more stress than I'm able to handle. With more time and effort working on myself I have developed a higher tolerance to the stress I experience around my folks, but I've a long way to go yet.
Sounds like you're best devoting as much energy to continue working on improving your own health/psychology/QOL as opposed to devoting that effort to repairing familial relationships. But it's a balancing act for sure, as just ditching family isn't really appropriate either.
It's telling you have the pull to spend more time in nature - that means you've both identified healthy ways of coping and still have a need to put your primary effort into taking care of your own wellbeing prior to being there to support some family members. This might make one feel like one isn't good enough or doing enough as a son or relative, but it's important to come to terms with. Because you'll be far less available to be there for family when you are struggling to just be there for yourself.
How are you feeling about the holidays coming up?
Those are very often are among the most stressful times of year for many people. Being proactive protecting yourself from sources of stress that increase around this time of year is always really important for me. Sometimes that means limiting the amount of time I spend with family, but it also means making sure I make sure to take good care of myself when I do chose to spend time with them. I often feel like I wish I could spend more time with family and continue putting my efforts into creating healthier, more fulfilling relationships with my parents, but like I said if I'm not able to take care of myself I'm not of much good to them either. It's just the reality I live with.
The positive side of that is that, as I continue to put my own health first in all my relationships with other people, I continue to develop more fulfilling, healthier relationships with my family. As my own health improves, I become more of the friend and family member - and especially the kind of son - I so want to become. It's slow going sometimes, but nothing if not a process. Progress, not perfect, right?