Whether you confront her now or after birth, make your preparations and be prepared.
It is not always possible for a BS to make preparations, sometimes a BS just walks in on WS and OM unexpectedly and has to confront immediately or something happens and a BS who already knows what is going on just blows up. There is no right or wrong way, but usually it helps to have a plan and your words ready and when you have made preparations.
First, what is it that YOU want, have you already thought about that? Would you like to aim for R or do you think it is unforgivable what she has done? Sometimes, here on SI it is said that you can D, and re-marry later if you would like to do so, or that you can file for D and retract the papers on a later moment should you want to. If you want R, then you better understand that you should not totally destroy her with your words and actions, but to keep a constructive mindset and a constructive conversation with her. Should you firmly opt for D, then would that be necessary now?
Second, what will you say? Another member here on SI, named Bigger, has a good set of words for it, and he has mentioned the set of words a lot word-for-word in other posts about confrontation. You should look the exact words up in his posts in one of the other topics on JFO, they are really good.
Third, have you already thought of what you can expect when you will confront? Should you confront her, would she then run to OM? If you expect that, better throw away her passport. Also, have you already seen in other posts where confrontation happened, what may happen or usually happens? Usually, the WS will attack the BS when confronted, and say things such as 'You are a bad guy because you invaded my privacy, you were never a good man to me, you did this or that. Do not believe these things, they are to make you the bad guy while you, of course, are not the bad guy. Also, such things usually are said to deflect and are not the real issue, so do not invest effort in them and stay focused on the real issue (the cheating by WS). Further things that you can expect are denial/gaslighting, lovebombing, or self-harm. Rarely, the WS says what a BS hopes the WS will say, "OMG what have I done, I was so stupid and never will do this again, I LOVE YOU!!!". And even if the WS says this and you will forgive, you should stay vigilant, because the WS has an emotional attachment to OM. Be prepared that the WS will throw sand in your eyes, lie, deceive, attack you, and so forth. You have to defuse, all the while staying calm. Staying calm is truly critical and of vital importance, if you lose your temper, things will quickly go from bad to worse, stay calm at all times!
Fourth, have you thought about consequences for her so that she will learn the hard way not to continue the affair? Here on SI, exposure to family and friends is regarded a good consequence. Exposure does multiple things, for you it makes life easier because you can freely talk about it with others and receive social support, those others will then also keep their eyes on her, and she has received a blow in her social reputation for the cheating and hopefully will hence not continue the affair because of it.
Fifth, have you already thought about what should happen after confrontation? I think it is perfectly fine for you to phone her parents after confrontation, inform them, and to ask them to come and pick her up, so that she will be in their safekeeping (and not your responsibility at that moment). And what about you?, what will you do?, where will you go?, maybe inform a good friend to come and support you afterwards? Of course, you would want you and her to fall into each others arms and live on happily ever after, but that might not happen after confrontation, cool off individually?
Sixth, continue to work on making things safe for you; Legal advice, counseling/therapy for you as an individual, a plan for alternative housing for you or her (go and live with parents?), relocating your private money, research (copy/photograph those e-mails!), VAR in car, etc.
One lucky thing is that you have clear evidence, so trickle truth will less be in play in your case. Also, as another member (Freeme) said, it can be the case that all this is just 'living a fantasy' for her, that does not make it less painful but might increase your chances for R.
You are already doing a great job and SI is here for you, confrontation will happen sooner or later, thus make your preparations it will help you. Strength brother!
[This message edited by babypuke at 10:32 AM, April 27th (Friday)]