This should really be answered for you by a health professional with health knowledge and specific knowledge of your situation.
In the absence of those I will mix in.
It was harder when I was diagnosed. lactaid pills nor milk did not exist. I ate no dairy for years.
Really, most people can get away with a little, assuming this is an intolerance (stomach ache) and not a true allergy that can kill you or make you REALLY DANGEROUSLY SICK.
Cold or fatty foods are digested slower so your natural or added enzymes get to work longer before they are messed up. Hot dairy would be much worse.
Some yogurts can be less problematic because the lactose is digested into the sour taste of yogurt. Some other yogurts add too much milk powder as a thickener and this includes more lactose.
I use a foreign product called LACTRASE, good luck finding it. It works. I use huge amounts of Lactaid brand milk. NOT CHOLOV YISROEL! It works great if it is marked 100% lactose free. I would never drink regular milk as the pills are not that strong to deal with regular milk.
If you just got the diagnosis relax. It is not life altering. Chances are after a long period some intestinal inflamation will become less and other foods will be more easily digested. Always be suspicious of other foods that always make you sick, you might also have an intolerance to othr sugars.