if i've got a project, the rate of return is 8%, but if my borrowing cost is gonna go up to 7%, it simply does not reward my risk, in which case I will not borrow.

What you presented is more like a mortgage case where one plans to buy a house in the near future. So it depends on which impact is greater.

But on the other hand, from a saver's point of view, more people will save instead of invest, which will cool the ecomony.