Syphilis acquired by whom first. Help?

Gud nun doctor. Im in need of a help I got married in 2017 and 8 weeks i found that im pregnant and blood tests showed vdrl positive. My husband was tested and found positive then. Physician suggested tpha and i was negative 0.2. My husband was reactive 1.8. Since i was negative i was lethargic. After a month i still wanted to cross check and did a tpha showed titre 4.51. Then i consulted again and got 3 shots of benzathine penicillin 2.4 lakh units 1 week apart. While he took 1 dose of it and said that doctor said its enough. Is it really enough? And after all these years, now he is suspecting that i contracted infection to him and a big family issue is going on which might lead to divorce. I consulted infectious diseases consultant 8 months postpartum to ensure that my son is also ok. But i was asked to come after stopping breast feeding. I Couldn't follow up. Now, i really want to know who acquired the infection first. Will the first titers help?