I'm 20 years old and currently pregnant with my first child. Before I found out the gender, I would watch porn, even though I do have my boyfriend and he doesn't know about that. When I found out that I'm having a boy, they also told me he has an abnormality that can be deadly and will need surgery when he is born. I felt devastated when I found out about that and felt that it was my fault. I promised God that I would not watch porn ever again and be a good momma to this baby boy. Well, I'm 8 months pregnant now and recently I've been having the temptation to watch porn. I have watched a few short videos. Trust me, I do feel horrible because I feel like God will punish me through my baby, and I really don't want that. I want to become a good mom to my baby boy, and I don't want to watch that bad stuff ever again. Will He forgive me?
You raise more issues than I think you realize, so let's try to sort them out, though I probably won't be able to address all of them.
The reason pornography is wrong is that it contains dangers. All sins involve problems that are disguised by the instant gratification of the sin. Pornography is sinful because it corrupts the concept of sex between a husband and wife. "Finally then, brethren, we urge and exhort in the Lord Jesus that you should abound more and more, just as you received from us how you ought to walk and to please God; for you know what commandments we gave you through the Lord Jesus. For this is the will of God, your sanctification: that you should abstain from sexual immorality; that each of you should know how to possess his own vessel in sanctification and honor, not in passion of lust, like the Gentiles who do not know God" (I Thessalonians 4:1-5). We are here to please God and not ourselves. What God wants from us is to be set apart as special (or holy or sanctified) people. Sin, such as fornication, corrupts the person involved in sex outside of marriage. Anyone can have sex, but God's intention is that sex is supposed to be something special, something shared only between a husband and wife bound by a covenant of marriage. Thus, fornication cheapens and makes common what should be special, and in turn, cheapens the people involved in it.
Since fornication cheapens a person, the things that lead to fornication, such as "passion of lust" or pornography, also cheapens the person. Among its many faults, pornography warps how a person views people and sex. Sex becomes something you do for selfish reasons instead of being a giving act to please your spouse. Pornography also causes the viewer to see people as objects for sex. Relationships become shallow with emphasis on the physical instead of the character of the person. In part, the reason you are having sex with a boy you are not married to is that pornography taught you that relationships are about personal lust and passion.
The pornography led to fornication and fornication led to you being pregnant. I don't know what led to the birth defect. There are many possible reasons: genetic defects, drugs, alcohol, etc. can all play a role.
I'm glad you are committed to no longer looking at pornography, though you are doing so for the wrong reasons. This isn't about the fact that your son has a problem. Pornography is wrong in and of itself because of the problems it causes you spiritually. That is why you should quit it. The promise makes no difference. You merely promised what you were already commanded to do. You don't want to be involved in it and you don't want to teach your son to be involved in it either. For that matter, you don't want to teach your son that it is all right to get women pregnant just because he wants to have sex.
I hope and pray that the surgery is successful. However, never blame God for the difficulties in your life that came about by your own poor decisions. This is an opportunity for you to grow and change. Make the most of it. Become a special person -- no more sex until you are married and no more pornography.
All sins are forgivable if you are willing to change your attitude about the sins and change your behavior. That is what repentance is about. "For observe this very thing, that you sorrowed in a godly manner: What diligence it produced in you, what clearing of yourselves, what indignation, what fear, what vehement desire, what zeal, what vindication! In all things you proved yourselves to be clear in this matter" (II Corinthians 7:11). Become a real Christian and not merely someone who calls herself a Christian but doesn't live the life.