In the end, only you yourselves can decide what your priorities in life are. It will fit. Due to the high equity portion, even the absolute worst case (your husband losing his job, he finds nothing new for a long time that pays enough, the house has to be sold) will not ruin you – and the risk is really very manageable/non-existent, moreover, the installments can be adjusted and in the greatest emergency, you can still sell the [ETW] or send yourself to full-time work.
What doesn’t quite add up for me: the [ETW] with 80 sqm brings in 1000€ cold rent – but a move-in ready detached single-family house is available for 750k? The ratio somehow doesn’t quite fit, right? Not that even bigger investments will be coming up for you there?