I'm a big dummy :S

So my son was recently diagnosed with a peanut allergy. Previous to this I have always enjoyed a pbj or peanutbutter milk shake. I have mostly cut it out since we are still nursing. But tonight without thinking I shared a peanutbutter milkshake with my hubby. I didn't even think about it. Now I'm panicked because I don't have a bottle but he does have his soy milk. I've never noticed a reaction before he was diagnosed but now I'm a big panic pants :-/ I'm not sure what to do. How long will it hang around in my milk!?!