Window frame- sealant cracking, gap and draft

[annasz84]

This is corner of my kitchen window.I removed blinds and attempted to fill the holes but the chunk of plaster came off just below. Sealant is cracking all over the frame and in that place even come off easily. There is a draft coming from these cracks as well.
I'm going to repaint the kitchen anyway but how I go about fixing around this window?
Do I have to remove whole sealant? What do I use? Expanding foam and caulk?
Any produts recommendations?

 

[diy_fun_uk]

CT1 Adhesive & Sealant

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