Aw mate, that's sad.
I still remember the day, I had to hold n put to sleep one of my cats, broke me fkg heart. She'd developed a lung problems, almost over night, and could breath. I couldn't see her suffer.
You will get over her, but you'll always.miss n think of her. It's ok to get another, but a different breed n name, or you WILL compare. There a lovely dog in a shelter waiting especially for.you.