If you want investment, why don't you do some saving plan, for example, invest some money to buy HSBC monthly, it can have 10-15% return in long term. More stable than buy a house. Don't think about your husband will leave you. Trust & communicate are good weapons to maintain a good relationship.
But you said your husband don't want to moved out from current house, if you buy one by yourself and moved out yourself only, then what will happen???? he may be very angry. It maybe ruin your good relationship. I think you should convict your husband and let him know your concern-you cannot stand with the noise pollution from MTR and you can't sleep well. Cause buy a house is a big issue