I think the married woman I had an affair with is pregnant with my baby. What’s the right thing to do?

Before lockdown, I began an affair with a married woman, J. She told me I was her soulmate and no one had ever made her feel like I did. Those feelings were reciprocated. After much indecision and heartache, she left her husband and I left my wife so we could start a new relationship together.

Very quickly we discovered J was pregnant. That put a lot of pressure on our relationship. Although we had wanted a child together (her first, my second), the speed at which it happened made things difficult between us. I did not cope well, but I didn’t want the relationship to end.

A couple of weeks later she had a scan and told me that the child was her husband’s. She sent me a copy of the scan report, then ended our relationship. I queried the paternity – I had consulted a midwife and, given the dates, I believe the child is mine – but she became upset and told me she was sure.

I don’t know what to do. J is very clear that she wants a calm and happy pregnancy, without any additional stress. She is working hard to rebuild her relationship with her husband, who knows nothing about me. She has broken off all contact between us. I am heartbroken that the relationship is over, but I want to respect her wishes and not upset her. I intend to put money aside every month for the child so that if and when I need to provide support, I can do so. What is the right thing, ethically, to do?

This week I consulted not one but two experts to help me answer your letter. First, I wanted to find out legally what your rights are and, second, to think about this from a psychological point of view.

Mena Ruparel, chair of the Law Society’s family committee, explained that when a couple are married (and I presume J didn’t get a divorce), there’s a legal presumption that her husband is the father. This is called the presumption of legitimacy. So in order to refute that, you would need to ask J to agree to a DNA test on the baby once it’s born (you can do it privately without her husband knowing, but, of course, if it is yours, then he’d need to know). If she won’t agree and if it’s something you want to pursue, apply to the courts – a declaration of parentage – explaining that you have good reason to believe you are the father, and if the court agrees, it can order DNA testing.

If the child is yours, then that has various legal implications, such as contact, child support, etc. You can make that application of declaration at any point after the child is born, but I imagine if this was a path you wanted to take, you would seek to do it soon after the child is born because the longer you leave it, the bigger the impact on the child’s life.

Those are your legal rights. But what’s legal and what’s ethical aren’t the same thing. Hannah Sherbersky, a psychotherapist, thought you should wait until after the baby is born. “Ethics is very context-determined. It’s ethically right to do the preparatory work, as you have done [thinking it might be yours and wanting to stand by J and putting money away] but it doesn’t mean you have to act on that right now.” Sherbersky thought that while it was noble you were thinking about the unborn baby, it was also clear that J is within her rights to ask to be left alone with the pregnancy.

Sherbersky also wanted you to think about your own wife and first child. Is there any reparative work being done there? What are the implications for them if J’s baby is yours?

A child has a right to know who their father is for all sorts of reasons, but this is a decision only you can make because the ramifications will be yours to live with. There is little point in throwing a grenade into J’s life unless you are sure you can be there for the long term if the child is yours.

“Sometimes,” Sherbersky said, “when we don’t know what’s the right thing to do, it’s useful to work backwards – think about what would be the wrong thing to do. Here it would be to hound J at this point in her pregnancy and make demands.”

I suggest you see a counsellor to talk this through, not least to work out what you really want. And once the baby is born, mediation may be something for you and J to think about.

Every week Annalisa Barbieri addresses a family-related problem sent in by a reader. If you would like advice from Annalisa on a family matter, please send your problem to ask.annalisa@theguardian.com. Annalisa regrets she cannot enter into personal correspondence. Submissions are subject to our terms and conditions.

Conversations with Annalisa Barbieri, a new podcast series, is available here.

Comments on this piece are premoderated to ensure the discussion remains on the topics raised by the article. Please be aware that there may be a short delay in comments appearing on the site.