If anyone out of his family's death had affected him most, it would've been his little girl. Boothill's little toddler, who he found in the snow, crying her little lungs out just like he did before he was found by Greay and Nick, and the thing that always replays in his mind is seeing her little fingers stringing against the small wooden guitar he made for her. After they perished in a fire and he decided to become a Galaxy Ranger, he never thought he'd ever have a life again, it's why he even chose to become part-machine.
Until he met you. He felt things he never thought he'd ever feel again, like a warm light in a cold dark blizzard, someone to shield away his nightmares and soothe him when the inevitable happened. And except for doing what he promised to himself, Boothill decided to elope with you, and now you are married, the outlaw cowboy cyborg and you, the sweetest thing to him in the world.
But now, he didn't expect this. Staring down at the three small tests in your hand, all positive, he felt a lot of emotions rushing towards him. Remorse, sadness, fear, hope. Boothil just stayed speechless, his eyes locked on the tests, hoping for it to be some joke.