Peter Pan wrote:

So what do I need to put on it to stop it from taking over the rest of my
yard?

how much physical labor are you willing to
apply in order to have a nice green lawn?

the reason I ask is because there are several
approaches to control and eradication.

eradicate
verb transitive
1: to pull up by the roots

if you end up making the choice to use a selective herbicide
at this stage of the growth shown in your pictures, you'll end
up with one ugly lawn. the treated crabgrass will first go yellow
and then go brown. then, after the crabgrass is dead you'll have
a bare spot for awhile since most selective herbicides used on
fescue retard the growth and spreading of the fescue.

if you work your fingers under the crabgrass you'll find several
runners all going back to the same root source. after several
mowings of crabgrass the runners will put down roots of their own.
if the runners have not put down roots pulling the source root is
not all that difficult. takes some time. wet the ground and it
will be somewhat easier.

if all the above seems to be the incorrect choice for you. do an
over seeding with fescue seed in the early fall when you notice the
HOT weather crabgrass beginning to go DORMANT. pamper your new seed
with some starter fertilizer and adequate water. in the very next
spring before your air temps get high enough to bring the crabgrass
out of it's DORMANCY, as well as sprout all the seeds it made and
dropped into your lawn, apply a good quality at the correct quantity
of a pre-emergent designated for crabgrass.

good lawn care is always filled with choices.