My colleague has recently left and I agreed to take on some of their workload. We had a few handover sessions but when I was asking questions, my colleague was quite defensive. It is only now that I am doing the work that I realise how poor the handover was and there are significant gaps in my knowledge. I have a meeting with my manager this week and I'm stressing that this will reflect badly on me. I've spent hours this past week (often into the evening) trying to get a grip on things but the more I look into it, the more queries I have and it's driving me crazy.
Any tips on how to handle this?