Can I replace this rubbery strip around my windows

What you're looking for here is called glazing. We offer a decent selection of replacement glazing bead, but most of ours is rigid. You say in your post that yours is rubbery, which is a little more uncommon for this kind of window.

Either way, before I can suggest a replacement I'll need a clear photo of the end profile in undamaged condition. I know that yours is very brittle so that will be easier said than done, but please try your best. Figure that the more damaged it is, the less likely I'll be able to find a good match. The video below will go into more detail as to exactly what I need.