I am so sorry to hear you are struggling and wanted to reply so you know you are not alone in this.
My son has OCD centred around health, contamination, poison and fear of death. He has been unable to manage any therapy, because of his overriding need to stay safe, plus having ASD, makes it impossible for him to do the necessary work.
His reaction has been similar to yours, in that he doesn’t want anything coming into the house from outside, even to the extent that he doesn’t want presents or cards for his 18th birthday. Initially we had big problems with him wanting to control the whole family as well, but that has eased a bit now.
I think the advice to recognise what you can reasonably control and then to do your best to distract is spot on. When he was attempting therapy we were advised to treat each situation like a court-case, weigh up the argument on both sides only dealing with confirmed facts from reliable sources and through that work out what the genuine risk level was. By working through that process (we tend to do it like a flow chart) it can bring down acute panic levels and get him back to manageable levels. In the beginning it could take up to 4 hours to go through it all - often in the middle of the night - but now he’s used to it we can get through it really quickly. So, in the current situation, what has helped is us making sure we do our research from reliable sources only (not social media) so he has the facts about how COVID is neutralised by simple soap and agitation and why. That way he knows what the actual risk is and also how much/little he/we need to do to minimise that risk. It also makes the virus less scary when you realise you can kill it with soap. Also the research about how long it can actually live on different surfaces. This means we can have meaningful discussions about the situation and the actual risk factors and agree a level of household care that he can cope with, but doesn’t expect us all to become as obsessive as he is. We have asked him to step away from Google and he doesn’t do social media, as he knows it is no good for him. I suspect he is still Googling, as it’s part of his cycle, but we have made sure we’re armed with the facts we need to nip any incorrect info in the bud.
As you’ll know, with OCD it doesn’t help the sufferer if family members comply with and support the obsessions or rituals, so your mum increasing her vigilance and handwashing and routines, over and above what is expected of all of us in the present situation, in her own home, wouldn’t be the right thing to do. I totally understand what you’re saying about your need for control leading to arguments, as we have the same problem and it’s the last thing anyone needs, especially when you’re all stuck at home together.
We have reassured him that we are all washing our hands regularly for the right amount of time, using the right method. Taps, door handles, light switches, toilet flush, fridge doors and handles and kitchen surfaces get cleaned regularly anyway. I’m afraid we do have to be firm but fair if he starts up, reiterating that we are all taking sensible precautions and he cannot expect the same levels of hypervigilance and obsession from all of us that he has himself. I have made it clear that I will do the above, but if he wants the house bleached top to bottom he’ll be doing it himself (which will never happen as he’s actually got huge issues with how dangerous bleach is as well). He doesn’t touch door handles at all, he uses his clothing over his hand to grab the handle if he has to, does taps with his elbows and has other things he does that we don’t, but he knows he can’t expect us all to do the same. Historically he would ask other people to open or close doors for him, know he knows we won’t enable him in that way, as it doesn’t help.
If you are struggling with your mum handling post and parcels, is there a middle ground you can agree on such as leaving it in a box somewhere for 24 hours, then reading it and washing hands afterwards? We sometimes find talking it through, using the facts and flow charts to come up with a system he can cope with, which doesn’t expect us all to be obsessive as well is the best way to keep the status quo. We do have to be careful to make sure that the system doesn’t then become ritualised and he starts hyperfocussing on it. So it has to be sensible, reasonable and manageable.
Are either of you having to go out? We have been home as a family (5 of us and two huge dogs in a tiny house) for four weeks now and his anxiety levels reduced once he knew we were past the 14 days without any of us coming down with it. Unfortunately I then became ill with something unrelated and ended up having to go out to collect a prescription, so his anxiety is up again now, despite me taking every possible precaution and him agreeing I couldn’t have done more.
He did agree to walk down the road with his dad and the dog (5 minutes there, five minutes back) a couple of times initially, but it really pushed his anxiety levels through the roof and he refuses to go now. He also won’t go in our garden, because of a previous issue with him thinking it is contaminated following some building work, so he’s not going outside. I know this isn’t good for him, but we have to find a level we can all live with, so I have upped his Vitamin D intake and will pick my battles.
He is choosing to spend most of his time in his room, although he does share it with his brother and he feels safest in there. He can get a bit overwhelmed with being around the whole family too much anyway, due to his ASD. We’re respecting this choice and also his preference that we don’t go in there unless absolutely necessary, although he is fine with his brother going in.
Are you on any meds? My son had just had his meds raised and I think without that having happened he would be a lot worse. If not, would they consider perhaps prescribing something like Sertraline to help you through this?
Re distraction, I think this really helps my son. We’ve signed up for a couple of extra streaming services, he has college work to do and is playing computer games with his friends online. Watching lighthearted comedies seems to help him a lot. Unfortunately, due to his ASD, he has a limited range of interests, so things like reading, making things, baking, etc aren’t options. I’m not sure what you like to do, but things like making things/craft, drawing/art, colouring in, jigsaws and reading can really help, as they require focus and concentration, that stops your mind wandering. Personally I’ve found buying a new game for my ipad and challenging myself to beat x number of levels is a good distraction. I’ve been ill in bed this week and have found old black and white films on Britbox (got the free 30 day trial) have been a good distraction.
Overall, this is a very difficult, unprecedented situation. People who don’t have OCD around health and contamination are struggling, so it is bound to be really tough on people like yourself and my son and give and take is required to find a way through that works for everyone. Be kind to yourself, recognise things are going to be tough for a while and don’t try and tackle everything all at once, maybe decide an area that’s causing a lot of friction between you and your mum, talk that through calmly, maybe use the court case/flow-chart model and come up with a plan then trial it, before moving on to the next thing you feel you need to address.
Good luck with it all, I hope things improve for you and you manage to find a way to live through this bizarre new normal we’re all dealing with at the moment.