If you ever wanted to find out just how much of a horrible person you are, become a parent. Then, if you're still not sure, become a parent again. I'm not positive, but I think you can lather rinse repeat until you're totally convinced on this one.
Before I had children, I would have sworn that I was walking proof of the fruit of the Holy Spirit - in some nascent form, at least. To some degree, I believed deep down, I am loving, joyful, peaceful, patient, kind, good, faithful, gentle, and okay maybe I struggle with self-control.* The good news (non-capitalized) is that I now suffer from none of those delusions about myself.
I know now that I am a horrible person.
Children are little sanctity makers, I had heard. The family should be the school of love, John Paul the Great said. I nodded along while reading these things in my copious amounts of free time, right before I took a leisurely shower and had a full night's sleep. The fact is, when my life was generally of my choosing with few responsibilities, it wasn't very hard to be the person I wanted to be. Given that I normally had a great deal of sleep, ate what I wanted, had time to work out, pray, and see my friends, I did not struggle to be virtuous.
In other words, previously, I had never really been virtuous at all - because being virtuous is having a "firm and habitual disposition to do the good." (Catechism) Turns out, my disposition towards doing the good was neither so firm nor habitual. It had been shallowly developed in an easy, rather selfish stage of life and as soon as it faced true hardship, my virtue revealed itself to be just an expression of my temporary wants, instead of a true habit.
There isn't a single virtue I have even come close to mastering, or even just getting a grip on. The ones I thought I was starting to approach mastery with have fallen to sub-par levels, and the ones I thought I might be gaining some proficiency in have completely disappeared from my radar: self control? what even IS that? pass the leftovers of the cross cake, please.
This starting point - true humility, knowledge of one's sinfulness - is actually step one for most spiritual exercises or true growth in the faith. So I guess what I'm saying is: it took me until age 30 to even get to step one on the path to mastering virtues that I thought I had mastered 8 years ago.
Cheers to you, vocation of marriage - you'll get me to Heaven, eventually.
*Obviously all of that is like a huge red sign going DING DING CONFESS PRIDEFULNESS, but hey adult converts have a steep learning curve, okay.