DotEnv.cs

using System;
using System.IO;

namespace YourNamespace
{
    // adapted from https://dusted.codes/dotenv-in-dotnet
    public static class DotEnv
    {
        public static void Load()
        {
            var currentDir = Directory.GetCurrentDirectory();
            var root = Directory.GetParent(currentDir).Parent.Parent.FullName;
            var dotenv = Path.Combine(root, ".env");

            Load(dotenv);
        }
        public static void Load(string filePath)
        {
            if (!File.Exists(filePath))
                return;

            foreach (var line in File.ReadAllLines(filePath))
            {
                var parts = line.Split('=', 2,
                    StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);

                if (parts.Length != 2)
                    continue;

                Environment.SetEnvironmentVariable(parts[0], parts[1]);
            }
        }
    }
}