Work Colleague

I’m struggling with my thoughts about working alongside a colleague and am feeling frustrated and angry. And I’m not getting the results I need in terms of work deliverables.

My underlying thought about this colleague is that they are difficult and don’t do what they say they will do at the time they have said they will do it.
Thinking of my colleague as ‘difficult’ is not a helpful thought as it makes me feel resentful, angry and resistant. I often put myself in the position of waiting and waiting for this colleague to do something to a deadline (which they don’t do). I feel powerless and know that I think of myself as a victim when this happens. My colleague is more senior and I am client facing so feel responsible to the client to make things work.

I am trying to take full responsibility for this situation and think “this is part of my job to manage this”; “this is my responsibility”; “of course my colleague isn’t going to do [x] on time – why do I think they will” but I can’t see how I have any power to affect the result I want and need (which is to run a course to an agreed schedule and I am dependent on my colleague to deliver certain elements). I can see that I am putting myself in a position where I feel powerless but don’t know where to go next.

A typical model is:
C [colleague] said “I will get in touch with you tomorrow to assign groups”. The next day, [colleague] does not get in touch and I send three emails asking for this information
T [colleague] is a nightmare
F annoyed
A fume inside my head. Stress about what the client is thinking. Start to draft emails to the client to cover the situation. Spend all day wondering when this information is going to arrive – checking and rechecking emails. Construct unhelpful stories about how disrespectful this colleague is of my time. Resent that I feel responsible to the client without having any power to resolve the situation. Tell myself I should be able to handle my colleague differently and if I was a better project manager this wouldn’t happen and this is all my fault. Construct unhelpful narratives where I am a victim of this situation. Complain about colleague to co-workers (in my head only). Don’t focus on other work properly because I am ruminating on the above and feeling immensely annoyed.
R I create a nightmare for myself