Anger, especially in a situation like this, is expected, natural, and healthy. Not having anger in this situation would be a problem.

If it's causing issues in your life, though, it's definitely worthwhile to consider taking some steps to improve your mental health.

Therapy's probably the obvious low-hanging fruit. You talk about "handling these feelings without making my partner feel guilty". That's something talk therapy would be really good at addressing.

Another approach you can take (and not mutually exclusive with therapy by any means) is a mindfulness sort of practice. Both being mindful of your feelings during your regular day/routine as well as setting aside some time to sit still and watch your thoughts can be very helpful. Here's one guide you could follow. But feel free to research and pick a method yourself if you prefer. (And you definitely don't need an app unless that appeals to you.)