What is the ruling on urinating in an unclean place where there is no water and it is not possible to sit, with the fear of urine splashing and obsessive thoughts after purification?

Wasaawis (obsessive whispers) are among the most evil ailments, and there is no cure for them except to ignore them. If you need to relieve yourself, do so in the proper place. And if Satan whispers to you that the place is not clean, ignore his whispers. If you are certain that there is impurity that you fear might touch you, then there is no harm in urinating while standing. It is not certain that you will be splashed with urine, and it is easy to avoid such splashes. If you doubt that you have been splashed with urine, the original ruling is that nothing has touched you. If you are certain of it, then wash the spot that was splashed. If you do not have water for istinja' (washing after relieving oneself), then use istijmar (cleaning oneself with stones or similar) by wiping three times with a stone or what serves its purpose. The religion of Allah is easy, so do not make things difficult for yourself.