I developed an allergy to peanuts in 2004. I've had 4 peanut related reactions, including the original time. Learned to be very careful.
Many people that are allergic to peanuts are also sensitive to tree nuts because the proteins are very similar.
Tree nuts are risky for me. Walnuts made my mouth itchy when I had too many as a kid. They are obviously high risk. My sister is allergic to them.
I haven't been tested due to $$$ but the reaction was obvious and one time was to fresh ground natural peanut butter - by itself.
I also react to the peanut oil. Skin contact gives me hives, so I will NOT risk eating it.
How I get by with it:
Read the whole ingredient label on all prepared foods. Very important.
Read allergen warnings. "This product made on shared equipment" or "May contain traces of... " .
Remember that allergen warnings are not standard.

They are still being phased in still and not on foreign foods usually.
Find out what kind of oil anything was fried in. Peanut oil is popular because it has a high smoking point. Turkeys are fried in it sometimes.
Snack foods are very high risk for contamination with peanut. Always read it.
Learned other names for peanuts. Groundnuts, Arachis oil, Peanut flour ( in Fearn's Carrot Cake Mix - I had no idea! )

Must check medicine and vaccine ingredients. Some contain peanut oil. Almost never use pharmaceuticals.

Avoid Thai food

and careful with other

Asian

and Indian food. Checkers is out- they fry in it.

Ask servers questions and stick to the lowest risk items I can find. A server that didn't speak English well served me a side dish of peanut sauce.

Read ingredients on beauty products, massage oils. India's beauty stuff uses it often.
I snack before a party/potluck or new restaurant so I wont be too hungry - in case there isn't much definitely safe food. People don't pay attention if it isn't their allergy!
Vitamin C flush, homeopathics & natural allergy stuff helped some.
I've used Benadryl for a reaction sometimes. It made me sleep for 12-16 hours afterwards.

ONLY for emergency.
Grocery shopping is very slow when you have to read labels. Good motivation to cook from scratch.
People assume you are being picky or don't take it seriously lots of times. So read for yourself.