That sucks . Playing devils advocate . The European white birch . Is well known to be prone to fail from . Disease and bugs . Especially in North America . Its popularity as a landscape tree . Stems from part nostalgia from Europeans . That move here . And more practical . It’s ease of propagation. And rapid growth . Plus less problematic in different soils . Here in Ontario Canada . There sold everywhere as landscape plants . But an old nature tree is rare .anything 20 years old or older. Has noticeable problems . My literally day one first job. When I purchased my house 21 years ago . Was cut down and burn . The 2/3 dead . One about 10 years old on my front lawn. So I don’t think you should beat yourself up about . Exactly what happened . Unfortunately the natives . Are mostly large leaved . Myself I started playing last year with some . Arctic birch . Betula nana . Or dwarf birch . These are small shrubs . And no they don’t have white bark , but they have 1/4 to 1/2 inch wide leaves . Arguable the most cold hardy . At usda zone 2 Deciduous tree on the planet . The cultivar Cesky gold is fairly easy to find . Somewhat argumentative what it’s exact history is . Including possible some European white birch Dna .