Traveling back to the US for the first time, quick question on CBP

Hi guys! Long time, no post. I've been over here in the UK for almost a year now, time flies! I'm getting ready to head back to the US for the first time with my husband (UK citizen). I know that when we travel through Heathrow, I'm allowed to go through the UK line with him.

For the US, I don't know what the rules are since I'm a citizen and he will just have an ESTA. Can I still use mobile passport (my favorite thing in the world) or do we need to go through the long line together? This is our first time traveling back, so neither of us really knows what to do when we arrive. We're also flying into Boston which I know has mobile passport, APC (which he CAN use), and the traditional lines.

Sorry if this has been asked a million times, I just don't see many people bring up mobile passport!

When we enter the US, my husband and I stay in the same line (US line).  I’ve never had an issue since you’re traveing as a family, they prefer you stay together in the line.

When we went to the USA at Christmas (December 2018-entered at Philadelphia) we were told to go to long/non-USA line, even though myself and our kids were American. I queried this with two different people and told the same thing.  Not sure had I just stayed quiet, likely would have been fine in the USA line.

Immigration guy chatted for ages about the Beatles (we're from Liverpool) so my line wasn't so bad!