OK, so he did not use a condom and ended up having a child he did not want, and learned from that experience and is now being careful with you, but you react to his being careful with you by feeling hurt. You feel hurt that he is so careful with you. Well, he is so careful with you not because he dislikes you or prefers her or anything else - he is so careful because he has LEARNED FROM EXPERIENCE! Which is a good thing - as a teacher, you should realize that the ability of learn from experience is the key ingredient of being successful.

So to the extent that you seem to show keen appreciation of "good learning situations", could you give him credit for processing his own good learning situation, rather than feel slighted by his being so careful?

Regarding putting the child first.

Imagine that you have done absolutely everything right. Absolutely everything. Finished the degree, got a great job, married, had a house with the husband, had exactly one child, raised him or her well, etc etc just basically everything has gone very very well and you are on your deathbed being very very old and proud of your life's achievements and ready to die in a peaceful, painless manner. And, you have a grown child. Who will be orphaned following your demise - imagine that the child's dad has already passed away after an equally successful life and in an equally painless, dignified manner.

From that locus, would you prefer that your child be left completely alone in this world or having a half-brother to lean on and converse with?

I can tell you a story of one of my close gfs.

She could not conceive a child. Was very successful in anything she touched, professionally or, basically, touched in any form, but could not conceive. Her husband did not have a fertility problem - she had. Her husband had a child with his first wife. After many years of trying, my gf and her H separated because she fell in love with a new man. Due to age, as she was in her late 30s, she immediately began trying to conceive with the new man. It did not work. Then, IVF attempts did not work - many of them. Finally, she conceived via IVF - a twin pregnancy. BTW you will need to read up on twins A LOT before you proceed with the IVF option that makes the likelihood of twins so high, because if you personally believe that there are so many issues surrounding the parenting of a second child, just wait until you read the literature on twins...

OK, so the new man has left his first wife and his 4 year old child to be with my girlfriend. His first wife was not happy about it - she wanted him back.

And then he had a heart attack at age 40 and died instantly.

And my gf had her twins and... was able to strike a relationship with the first wife of the man who died and with the older child of his. And she hosts visits on a regular basis, because she wants the half-brothers - her twin sons and the older son of the man who died - to bond and have each other for each other for the rest of their lives.

Try that - try working from the first principle that says that YOUR hypothetical child would BENEFIT from having a good relationship with his or her half-brother. Rather than put your bf's son first, put your own hypothetical child first and see what comes out of that way of thinking.