OP - I have been in your situation! Positive test even though periods hadn't stopped (was on pill), midwife estimated I was 16-18 weeks when she examined me, 'urgent' scan a fortnight later showed I was approx 33 weeks! Even the midwife was pretty gobsmacked. My little surprise is now almost 6 and we often joke that we've no idea how he stayed hidden so long as h is so loud and energetic 
Emotionally - it is terrifying. But it was just as, if not more terrifying when I had my other son as I had 30+ weeks to fret and worry about it all then. When I only had 5 weeks to go (had planned c section at 38 weeks) I had to just go into practical mode. I would tell everyone and let people help as much as possible with practical things. I'm glad your BF's family will be supportive. I had people I didn't even know messaging me saying they'd heard from my sister or from my friends that I needed baby stuff now and they had x and y to pass on if I wanted it. A colleague of my friend donated a barely used travel system she was going to give to the charity shop. My boss passed on her son's cot.
New babies do not need much 'stuff'. They need milk, warmth and cuddles. They also need a few baby grows and vests in newborn and 0-3m size, a safe car seat, a place to sleep (moses basket fine and cheapish) and either a baby sling or a pram (you can get that after the birth if necessary!). Buy packs of nappies and wipes/cotton wool... That's about it. Anything else is a nice extra but you don't need all the stuff you see in Boots, mothercare, or wherever. Honestly. We spent less than £100 on my son before he arrived and just bought anything else as and when we needed it. Saved a furtune compared to DS1 where u bought every gadget and fancy outfit going.
Being a parent in general is utterly baffling and terrifying at times for all of us. You've had less notice than most, but you can do this!
Also, you'll probably bounce back far quicker than I did at 35
. It was much more tiring than when I had my first aged 29. As others have said, join every group you can and let people help and support you as much as possible.