I have lone afib and started taking Xaltro. Does it matter which meal I take it with. The dose is 20, and scared of side effects.?

No interaction. Xarelto is one of the new anticoagulants which are safer than warfarin and they do not interact with food or other medications. You just need to follow pharmacist recommendations about best time to take it. .
Xarelto. Xarelto or Rivaroxaban is a direct factor Xa inhibitor. This thins the blood by effecting clotting proteins. Coumadin (warfarin) does too, but through a different mechanism. If you are on 20mg it is recommended to take it with food. It does not matter which meal, but I would make it the same meal daily.