I'm unable to satisfy myself that something become tahir.

if my body become najis and im taking bathvthen after bath I will wash all places and things in washroom as I know that water splashes by touching najis items are also najis. So i started washing all places after bath. It takes hours of time and lot of wastage.

If I go any shop and the cashier are even muslim, I start imagining that for sure some wet frozen items purchased by non muslims and they touch it so while scanning items, she also has touched it surely so she is najis and then my items are also najis. So after coming home I wash all items be it packed or unpacked items.

I'm unable to use english bathroom. I feel always that water are splashing on me while washing myself so I'm unable to satisfy and unable to ignore.

If I put my bare leg on the road, I feel it has become najis because again here also I started imagining that cars and vehicles are running on najis water and for sure with those tyres it run on all parts of roads and footpath also. People also walk with same najis sand and that sand will go inside my home along with my legs.

If I use indian products like oil, juices, biscuits, sweets I started assuming that there are all kafirs and for sure they have touched it because these things cannot be made without touching. I dont eat food in restaurants if I feel there is some kafir working in it be it a delivery boy or a chef.

There are lot of issues in my life related to taharat and najasat which ruined my life and my wife also got seperated from me due to this.

Now being alone and being in this disease I'm constantly losing hopes for living further.

I work in an office where kafirs are cleaners so I dont touch things. Even if I touch mouse and keyboard etc I feel I have become najis because there will be little moisture in my hands always.

Please give me suggestions and explain me my duties towards sharia in this matters.

Brother in faith, take this law seriously like a wajib act and a duty.
Every single thing is pure until you come to have knowledge of its impurity and Najasat.
How can one imagine when this is a fiqhi law initself, that one should see that whatever one claims is Najis, is really Najis, not merely imagined to be so?!
After bathing, do an Ahd to Allah that you willcome out, dry yourself and even if you touch anything, say, tawakkal ala Allah. Go forward and do all your activities. Infact time yourself to have a five minute bath and follow the footsteps of the Holy Prophet of Islam who never wasted water and many times did his wuzu with half a cup of water.
Even if you pick up any item in a shop, be it frozen or not, your hands dont get najis I can promise you that, because again the laws applies, seeing and not imagining. Even if they are kaafir walking around, ahlekitab ie christians are considered pak, As far as hindus are concerned, you can't imagine who touched and who didn't, so still you're not allowed to imagine. If you saw, then to wash only your hands that too for 10 seconds only should be done.
Try to take out a sadqa (charity) to avoid satanic imaginations which you should remember that shaitan loves working on ones imaginations and cannot come in the way of logical and rational thoughts.
Even if you have to use the english bathroom, remember the people who have put all their lives studying and researching to bring put the fiqhi islamic laws have allowed it so they ought to know more about water splashing or not, take their word like how one takes the word and prescription of a doctor, and stop imagining and asking for proofs again. Your responsibility is to follow the law and thats it.
As far as roads and footpaths are concerned, remember the sun is a purifying agent and everything whereupon the sun shines like the walls, roads, streets etc are pure as you go along walking so once again you dont have to worry even for a moment and consider yourself pure. Push these thoughts away through sadqa and seeking refuge in the Merciful Lord.
Avoid eating foods if you really think kaafirs would have cooked it, that should be the only best thing you could do because food makes the soul and the thoughts incurred by food have the greatest impact in our thoughts and actions. Trust all foods cooked by muslims by saying Bismillah before eating and again, consider it pure.
Even if the workplace you go in happen to be kaafirs, touch the items with ease and trust fully in Allah and follow your duty however difficult it may be at first. Before eating, wash your hands for 10 seconds only and never waste water. Remember all the people who suffer from shortages of water and dont even have enough to drink let alone bath or wash. Think of the accountability of the continuous water wastage. Repent and amend, start afresh and never lose hope. If you really truly want that, then follow all these instructions.
Last but not least, call you wife back and tell her to help you doing all this. It's a sure thing that she will do so in her right mind but dont turn back after making this firm decision to change for the better. Allah is with those who help themselves remember.
I pray you get better by the day.