Re: Complicated pension question
The usual thing..'pension'...you mean state, company or private (Pillars 1, 2 and 3) ?
1. State pension, will be based on National Insurance contributions you have / have not made
2. Company, will be based on contributions to your employers pension scheme
3. Private, like ISA in UK, or just called Pillar 3a here.
You say "I was told the UK would pay mine in while I wasn't working and raising kids" - that implies Pillar 1 (state). I don't know how 'NI stamps' (AHV) are accrued these days for married 'non-working' women, but it used to be that you would accrue none/very little in that situation (at least in UK). Maybe there is something fairer in Switzerland, which appears to provide some protection to SAHMs (see below, pillar 2). Maybe your husbands AHV contributions accrue you some benefit in Pillar 1 also. But I doubt very much the UK would be paying NI/AHV contributions on your behalf whilst your husband and you are non-resident and paying into the Swiss system. Unless you've been voluntarily buying class 3 (?) NI during that period.
Regarding Pillar 2, company pension, AFAIK in Switzerland you can only pay this if actually employed. Your 'ex' has been contributing via his employment, but the good news for you (as I understand it) is that those contributions (during the period he is married to you) accrue to you as a couple. On divorce a calculation would be made to split the assets and I assume your portion transferred to a blocked pillar 2 account. Anything your ex had accrued before marriage would be excluded from this.
Regarding Pillar 3, as a self employed person without contributing to Pillar 2, you can contribute as mentioned by Mullhollander each tax year (see the link already provided). I assume this is protected from being split on divorce in the way Pillar 2 is, but I don't know. The main benefit is the tax relief you achieve (contribution is deducted before tax applied to earnings).