You deal with regret by giving yourself grace.
God judges the heart and He knows yours. Remove the lies against yourself that the enemy has led you to believe; discover the truth of who you are now and how God sees you; and remind yourself of His truth. Ask God how He’d like to use the choices you now regret, for His honor and His glory. He uses all for the good of those who love Him. He’ll use this too.
“But he said to me, ‘My grace is sufficient for you, for my power is made perfect in weakness.’ Therefore I will boast all the more gladly of my weaknesses, so that the power of Christ may rest upon me.” 2 Corinthians 12:9
“And He who searches our hearts knows the mind of the Spirit, because the Spirit intercedes for the saints according to the will of God. And we know that for those who love God all things work together for good, for those who are called according to his purpose.” Romans 8:28