This thread is fascinating! I grew up in Suffolk and still have family there. I didn’t realise it had such a reputation for being unfriendly.
The town I grew up in has actually been mentioned upthread (but not recommended as a place to live 😂). It’s the kind of place where everyone is related to knows everyone. Many of the people I went to school with stayed in the area, had kids young and sent them to the same schools we all went to. Some people love it but it wasn’t for me and I can see why it would seem quite insular.
If I were moving back there now, Bury St Edmunds would definitely be my choice. Lovely town with good shops and schools. It doesn’t have the best train line but it does have direct links to Cambridge and Ipswich (and not such a big deal anyway if you’re WFH).
Ipswich is an odd place, it does have some nicer areas but there are also parts which feel very unsafe. The town centre is too big for the size of the town really, which I think leads to it feeling quite desolate. It has some good schools and some terrible ones, so catchment areas would be an important consideration.
None of the seaside towns are places I could imagine living with a young family. Some feel like holiday destinations (Southwold, Aldeburgh), some are very neglected (Lowestoft). Felixstowe seems to be improving.
Despite living in Suffolk for nearly twenty years, I don’t think I ever made it to Woodbridge. It does have a reputation for being “naice” though which I guess is both good and bad.
On the Essex/Suffolk border you could look at East Bergholt or Saffron Walden? I like both and I think they have good schools.
Having said all of that, I think relocating to Suffolk from Suffolk when your husband’s family don’t even live there anymore is pretty bonkers and I can see why you’re wary. Could you not plan an extended holiday there, maybe spend a month or so there in the summer exploring all your husband’s old haunts?