Lawn care help - I screwed up

So I think I fricked up my yard.

My yard was half St. Augustine, half bermuda and I think I accidentally killed the bermuda

Here is the St. Augustine



and here is where the bermuda was...



I sprayed atrazine and 2,4 D back in early March about 2 weeks apart, could that have killed the bermuda?

weeds are starting to take over since nothing was growing

is there anyway to fix this without re-sodding this year? should I just let the weeds take over and mow it often and re sod next year?

or put out some new topsoil and re-seed?

or keep fertilizing the crap out of the St. Aug so it spreads and eventually takes over the entire yard?