Is psychologically/mentally self harming yourself on purpose possible, where you look for things that trigger you (trigger your anxiety, stress or PTSD), not to desensitise yourself but to hurt yourself? Is there a word for it?
When it comes to self-harm, there is not a lot of information available about the emotional form, but there is a lot about the physical forms of self-harm such as self-flagellation (as a punishment and not for religious rituals), cutting, burning etc.
According to the mental health charity, Mind, self-harm is
when you hurt yourself as a way of dealing with very difficult feelings, painful memories or overwhelming situations and experiences.
The NHS states that
Self-harm is when somebody intentionally damages or injures their body.
Wikipedia expands on this by stating
Self-harm (SH), also known as self-injury, is defined as the intentional, direct injuring of body tissue, done without suicidal intentions.(Laye-Gindhu & Schonert-Reichl, 2005; Klonsky, 2007; Muehlenkamp, 2005) These terms are used in the more recent literature in an attempt to reach a more neutral terminology. The older literature, especially that which predates the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), almost exclusively refers to self-mutilation.
Also known as non-suicidal self-injury, or NSSI, the condition is classified in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (2013) as a "new disorder in need of further study,"
The definition in Wikipedia and used by the NHS and the APA has generally been used, but it is becoming increasingly recognised that self-harm can take on the form of emotional harm to the self. Emotional self-harm can be conscious or unconscious, and self-blame comes into this category.
As "itsrory" said in 7 Cups of Tea
Self-harm is often thought of as only physical (i.e., cutting, burning, etc.), but self-harm can also be emotional. Self-harm is just that, harming the self. Anything you do to intentionally make yourself hurt for reasons that are not socially acceptable, can be viewed as self-harm. Some emotional things people do that may be classified as self-harm are: staying in an emotionally-unstable relationship and purposefully doing things that you know may make you feel sad, upset, or depressed.
What I would add to the end of this quote is that you need to bear in mind that purposefully revisiting painful memories can come into this category, however if you are revisiting them in a therapeutic environment in order to deal with them, it is not emotional self-harm.
What is different between physical and emotional self-harm is that the physical, such as cutting and burning, is usually employed for emotional release, and not necessarily to punish; whereas the emotional self-harm punishes the person committing it. What makes this complicated is that exceptions to this include the fact that self-flagellation can be either punishment or emotional release, and revisiting painful memories can also be done for both. For example, someone who is not feeling anything may deliberately make themselves "feel" by revisiting painful memories in order to release the emotions trapped inside.
The only term I can come up with for emotional self-harm is self-deprecation
Laye-Gindhu, A. & Schonert-Reichl, K. A. (2005), Nonsuicidal Self-Harm Among Community Adolescents: Understanding the "Whats" and "Whys" of Self-Harm, Journal of Youth and Adolescence, 34(5): pp. 447—457