Mid spring I decided to aerate and overseed. Since i'm not really a lawn
guy I did not put down a pre emergent so now this summer my lawn has
been invaded with crabgrass.

You drew the wrong conclusion about this sequence of events. When you put out new seed in the spring (when the crabgrass seed is waiting for moisture) and then start to water it regularly, the crabgrass seed was the first to germinate. So it was you watering the new grass seed that caused the crabgrass invasion. This can be dealt with but we need more information about your yard.

You live in the transition zone where they grow all kinds of grasses. You could grow either northern grass or southern grass. What kind of seed did you put down? For the northern grasses like fescue, Kentucky bluegrass, and rye, fall is the best time to seed new lawns. For bermuda grass the hottest heat of summer (now) is the best time to seed. Do you know what kind of grass you already had?