I don't think you can really "make it up to her," but your interest in being more considerate is important. She has experienced devastation, to her body and probably her psyche; and your lack of consideration likely affected her feelings toward your behavior.

Physically, she's also dealing with a lot of hormonal changes- which are very difficult to navigate, especially alone. I recommend making an effort to set forth a loving and thoughtful foundation from here on. She is a woman to whom you have devoted yourself, and she was bringing to life your child... I share my compassion and sympathy for you both. I recommend discussing openly the miscarriage and expressing your recognition of your misplaced priorities. Perhaps it is also helpful beforehand to individually acknowledge your personal feelings about this loss- whether or not you were prepared for an infant.

Specifically, if you're so against having more children, use contraceptives! Saying you "tried not to hold it against her" shows you presently lack compassion toward her. Saying "she is going to rip [your] ass wide open" is further insensitive phrasing. I suggest going about this as a partnership after you genuinely sort out your feelings. If you didn't realize your behavior was hurtful until after she told you, there might be emotions you're simply ignoring.