Peter-

Read/reread SSH and continue to work on your post-flop play by playing, posting, re-reading. If he had JJ for the str8 that means that there was 4 to a str8 on the board at some point - learn to recognize this and adjust accordingly. Remember, sets can still be cracked so don't just get tunnel vision once you have a set. Have faith, keep at it!

Edite comments after reading OP's new position info: