@gesu I just wanted you to know that I understand how you feel. My 16 year old son has suspected OCD, although not fully diagnosed yet and our life is very similar to the one you describe. It’s incredibly hard to live with, no matter how much you love someone.
He also has ASD and the combination of rigid thinking, inability to see things from other’s perspectives and the OCD itself presents as a totally selfish, self-obsessed individual who doesn’t care how much they are negatively affecting the lives of others. Except I know that isn’t the case, as I have sat up through the night so many times with my son while he sobbed that this isn’t something he can control, that he doesn’t want to upset us, he really can’t help it. Reading your description of your sister’s behaviour rang a lot of bells and I wondered if there might be more than just OCD going on. My son can control his reactions around other people, but at home there is no control at all. This has always been the case with his ASD as well and not unusual in people who have ASD.
In the example of the friend that dropped the phone, his anxiety and stress levels would have gone through the roof, but he would never have shown it in public, he would have come home and put his clothes in the wash, but by that time the immediate adrenaline reaction to the situation would have been over for a while and he could be somewhat calmer about the situation. So, it’s not that he would have treated the friend one way and us another, just that he had no choice but to use every ounce of energy to control his reaction in public and by the time he got home the immediate danger had passed, he could do something about the perceived contamination to lower his stress levels still further and he would probably be completely exhausted by then as well.
He has had signs of OCD for many years, but these were repeatedly brushed off as just a manifestation of his ASD. As a result they have grown and intensified and the stress of his GCSE year finally tipped him over the edge to the point he could no longer manage it himself and we were unable to help him enough. It has taken a year to even start getting him help and we have had to jump through the NHS hoops of sending him on a general anxiety workshop for six weeks, where he was the only boy in a room full of teen girls and even getting him there and into the room was a huge battle. We - and he - knew it wasn’t what he needed (he has already been taught the standard anxiety management techniques but been unable to put them into practice, even with lots of help) but we were told he had to do it if he wanted further help (he didn’t really, as to him all his fears are logical and justified and he is convinced no-one will ever be able to help/make him see that, though they might be grounded in logic or facts, if he wants to have any sort of quality of life, he has to find a way to understand and live with the fact that none of us can control the uncontrollable). At the end of that course, which was useless as predicted, they agreed that he probably does have OCD and placed him on a 12-18 month waiting list for CBT. Meanwhile he spiralled and his obsession with contamination and being poisoned got completely out of control. He is terrified of death, injury and illness and anything that could potentially cause them - which is just about anything in life, so pretty all-encompassing at the moment. It’s 24/7 confrontations about what touched what, what might have contaminated what, clothes being returned to the washing basket without being worn because something might have touched them, food being thrown away uneaten ‘just in case’ refusal to touch certain things in the house or eat if others have prepared their food or eaten it just beforehand, rules about who can sit where at the table, who can put what where in the kitchen, etc. The list is seemingly endless and gets added to almost daily. We often have full on ASD-type meltdowns about perceived contaminations that simply haven’t happened and inevitably with 5 people in a pretty small house, tempers get frayed and we end up shouting, then I hate myself, because actually, all I want is for him to be happy and not live every moment of his life in fear. He is expending all his energy trying to control every single aspect of his - and our lives and as a result not having a life at all.
Two weeks ago I hit a wall myself, after waking up to him ranting at me from the minute I opened my eyes. I ended up calling my GP in tears, being triaged by and referred for therapy myself.
We have been lucky enough to be able to arrange some private therapy for him through my husband’s company, but that doesn’t start for another three weeks and I am not convinced he will engage with it. I have have had him home from school since the second week in June and he isn’t due to start college until the second week in September, he won’t leave the house and every day is a huge battle. I have read enough to know not to enable his obsessions, but at the same time, if I don’t or I try to argue and talk him round it results in a huge fight and potentially a meltdown every single time. Given that it’s something every 30 minutes to an hour - it’s totally exhausting and unsustainable and I sad to say our relationship is becoming damaged because of it. We have had to call NHS 111 for advice twice in the last two weeks (CAMHS crisis won’t help as due to his fear of dying he’s not a suicide risk) and take him in to be told they can’t help once.
I have two other children, one of whom shares a bedroom with him and has a physical disability which is both exhausting and painful and as a result he has been signed off school for the whole of the Summer term. I honestly don’t know how I/we am going to get through the summer holidays.
I honestly get how hard it is living in the situation you describe, I am just sorry I don’t have any useful advice for how you can help resolve the situation. 